Introduction to Razor Pages in ASP.NET Core

Create a Razor Pages project

Razor Pages

Razor Pages is enabled in Program.cs:

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddRazorPages();

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthorization();

app.MapRazorPages();

app.Run();

In the preceding code:

• AddRazorPages adds services for Razor Pages to the app.
• MapRazorPages adds endpoints for Razor Pages to the IEndpointRouteBuilder.

Consider a basic page:

@page

<h1>Hello, world!</h1>
<h2>The time on the server is @DateTime.Now</h2>

The preceding code looks a lot like a Razor view file used in an ASP.NET Core app with controllers and views. What makes it different is the @page directive. @page makes the file into an MVC action, which means that it handles requests directly, without going through a controller. @page must be the first Razor directive on a page. @page affects the behavior of other Razor constructs. Razor Pages file names have a .cshtml suffix.

A similar page, using a PageModel class, is shown in the following two files. The Pages/Index2.cshtml file:

@page
@using RazorPagesIntro.Pages
@model Index2Model

<h2>Separate page model</h2>
<p>
    @Model.Message
</p>

The Pages/Index2.cshtml.cs page model:

using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.Extensions.Logging;
using System;

namespace RazorPagesIntro.Pages
{
    public class Index2Model : PageModel
    {
        public string Message { get; private set; } = "PageModel in C#";

        public void OnGet()
        {
            Message += $" Server time is { DateTime.Now }";
        }
    }
}

By convention, the PageModel class file has the same name as the Razor Page file with .cs appended. For example, the previous Razor Page is Pages/Index2.cshtml. The file containing the PageModel class is named Pages/Index2.cshtml.cs.

The associations of URL paths to pages are determined by the page's location in the file system. The following table shows a Razor Page path and the matching URL:

Notes:

• The runtime looks for Razor Pages files in the Pages folder by default.
• Index is the default page when a URL doesn't include a page.

Write a basic form

Razor Pages is designed to make common patterns used with web browsers easy to implement when building an app. Model binding, Tag Helpers, and HTML helpers work with the properties defined in a Razor Page class. Consider a page that implements a basic "contact us" form for the Contact model:

For the samples in this document, the DbContext is initialized in the Program.cs file.

The in memory database requires the Microsoft.EntityFrameworkCore.InMemory NuGet package.

using Microsoft.EntityFrameworkCore;
using RazorPagesContacts.Data;
var builder = WebApplication.CreateBuilder(args);

builder.Services.AddRazorPages();

builder.Services.AddDbContext<CustomerDbContext>(options =>
    options.UseInMemoryDatabase("name"));

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthorization();

app.MapRazorPages();

app.Run();

The data model:

using System.ComponentModel.DataAnnotations;

namespace RazorPagesContacts.Models
{
    public class Customer
    {
        public int Id { get; set; }

        [Required, StringLength(10)]
        public string? Name { get; set; }
    }
}

The db context:

using Microsoft.EntityFrameworkCore;

namespace RazorPagesContacts.Data
{
    public class CustomerDbContext : DbContext
    {
        public CustomerDbContext (DbContextOptions<CustomerDbContext> options)
            : base(options)
        {
        }

        public DbSet<RazorPagesContacts.Models.Customer> Customer => Set<RazorPagesContacts.Models.Customer>();
    }
}

The Pages/Customers/Create.cshtml view file:

@page
@model RazorPagesContacts.Pages.Customers.CreateModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<p>Enter a customer name:</p>

<form method="post">
    Name:
    <input asp-for="Customer!.Name" />
    <input type="submit" />
</form>

The Pages/Customers/Create.cshtml.cs page model:

public class CreateModel : PageModel
{
    private readonly Data.CustomerDbContext _context;

    public CreateModel(Data.CustomerDbContext context)
    {
        _context = context;
    }

    public IActionResult OnGet()
    {
        return Page();
    }

    [BindProperty]
    public Customer? Customer { get; set; }

    public async Task<IActionResult> OnPostAsync()
    {
        if (!ModelState.IsValid)
        {
            return Page();
        }

        if (Customer != null) _context.Customer.Add(Customer);
        await _context.SaveChangesAsync();

        return RedirectToPage("./Index");
    }
}

By convention, the PageModel class is called <PageName>Model and is in the same namespace as the page.

The PageModel class allows separation of the logic of a page from its presentation. It defines page handlers for requests sent to the page and the data used to render the page. This separation allows:

• Managing of page dependencies through dependency injection.
• Unit testing

The page has an OnPostAsync handler method, which runs on POST requests (when a user posts the form). Handler methods for any HTTP verb can be added. The most common handlers are:

• OnGet to initialize state needed for the page. In the preceding code, the OnGet method displays the CreateModel.cshtml Razor Page.
• OnPost to handle form submissions.

The Async naming suffix is optional but is often used by convention for asynchronous functions. The preceding code is typical for Razor Pages.

If you're familiar with ASP.NET apps using controllers and views:

• The OnPostAsync code in the preceding example looks similar to typical controller code.
• Most of the MVC primitives like model binding, validation, and action results work the same with Controllers and Razor Pages.

The previous OnPostAsync method:

[BindProperty]
public Customer? Customer { get; set; }

public async Task<IActionResult> OnPostAsync()
{
    if (!ModelState.IsValid)
    {
        return Page();
    }

    if (Customer != null) _context.Customer.Add(Customer);
    await _context.SaveChangesAsync();

    return RedirectToPage("./Index");
}

The basic flow of OnPostAsync:

Check for validation errors.

• If there are no errors, save the data and redirect.
• If there are errors, show the page again with validation messages. In many cases, validation errors would be detected on the client, and never submitted to the server.

The Pages/Customers/Create.cshtml view file:

@page
@model RazorPagesContacts.Pages.Customers.CreateModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<p>Enter a customer name:</p>

<form method="post">
    Name:
    <input asp-for="Customer!.Name" />
    <input type="submit" />
</form>

The rendered HTML from Pages/Customers/Create.cshtml:

<p>Enter a customer name:</p>

<form method="post">
    Name:
    <input type="text" data-val="true"
           data-val-length="The field Name must be a string with a maximum length of 10."
           data-val-length-max="10" data-val-required="The Name field is required."
           id="Customer_Name" maxlength="10" name="Customer.Name" value="" />
    <input type="submit" />
    <input name="__RequestVerificationToken" type="hidden"
           value="<Antiforgery token here>" />
</form>

In the previous code, posting the form:

• With valid data:

  • The OnPostAsync handler method calls the RedirectToPage helper method. RedirectToPage returns an instance of RedirectToPageResult. RedirectToPage:

    • Is an action result.
    • Is similar to RedirectToAction or RedirectToRoute (used in controllers and views).
    • Is customized for pages. In the preceding sample, it redirects to the root Index page (/Index). RedirectToPage is detailed in the URL generation for Pages section.

• With validation errors that are passed to the server:

  • The OnPostAsync handler method calls the Page helper method. Page returns an instance of PageResult. Returning Page is similar to how actions in controllers return View. PageResult is the default return type for a handler method. A handler method that returns void renders the page.
  • In the preceding example, posting the form with no value results in ModelState.IsValid returning false. In this sample, no validation errors are displayed on the client. Validation error handling is covered later in this document.

  [BindProperty]
  public Customer? Customer { get; set; }
  
  public async Task<IActionResult> OnPostAsync()
  {
      if (!ModelState.IsValid)
      {
          return Page();
      }
  
      if (Customer != null) _context.Customer.Add(Customer);
      await _context.SaveChangesAsync();
  
      return RedirectToPage("./Index");
  }
  

• With validation errors detected by client side validation:

  • Data is not posted to the server.
  • Client-side validation is explained later in this document.

The Customer property uses [BindProperty] attribute to opt in to model binding:

[BindProperty]
public Customer? Customer { get; set; }

public async Task<IActionResult> OnPostAsync()
{
    if (!ModelState.IsValid)
    {
        return Page();
    }

    if (Customer != null) _context.Customer.Add(Customer);
    await _context.SaveChangesAsync();

    return RedirectToPage("./Index");
}

[BindProperty] should not be used on models containing properties that should not be changed by the client. For more information, see Overposting.

Razor Pages, by default, bind properties only with non-GET verbs. Binding to properties removes the need to writing code to convert HTTP data to the model type. Binding reduces code by using the same property to render form fields (<input asp-for="Customer.Name">) and accept the input.

[BindProperty(SupportsGet = true)]

Reviewing the Pages/Customers/Create.cshtml view file:

@page
@model RazorPagesContacts.Pages.Customers.CreateModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<p>Enter a customer name:</p>

<form method="post">
    Name:
    <input asp-for="Customer!.Name" />
    <input type="submit" />
</form>

• In the preceding code, the input tag helper <input asp-for="Customer.Name" /> binds the HTML <input> element to the Customer.Name model expression.
• @addTagHelper makes Tag Helpers available.

The home page

Index.cshtml is the home page:

@page
@model RazorPagesContacts.Pages.Customers.IndexModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<h1>Contacts home page</h1>
<form method="post">
    <table class="table">
        <thead>
            <tr>
                <th>ID</th>
                <th>Name</th>
                <th></th>
            </tr>
        </thead>
        <tbody>
        @if (Model.Customers != null)
        {
            foreach (var contact in Model.Customers)
            {
                <tr>
                    <td> @contact.Id </td>
                    <td>@contact.Name</td>
                    <td>
                        <!-- <snippet_Edit> -->
                        <a asp-page="./Edit" asp-route-id="@contact.Id">Edit</a> |
                        <!-- </snippet_Edit> -->
                        <!-- <snippet_Delete> -->
                        <button type="submit" asp-page-handler="delete" asp-route-id="@contact.Id">delete</button>
                        <!-- </snippet_Delete> -->
                    </td>
                </tr>
            }
        }
        </tbody>
    </table>
    <a asp-page="Create">Create New</a>
</form>

The associated PageModel class (Index.cshtml.cs):

public class IndexModel : PageModel
{
    private readonly Data.CustomerDbContext _context;
    public IndexModel(Data.CustomerDbContext context)
    {
        _context = context;
    }

    public IList<Customer>? Customers { get; set; }

    public async Task OnGetAsync()
    {
        Customers = await _context.Customer.ToListAsync();
    }

    public async Task<IActionResult> OnPostDeleteAsync(int id)
    {
        var contact = await _context.Customer.FindAsync(id);

        if (contact != null)
        {
            _context.Customer.Remove(contact);
            await _context.SaveChangesAsync();
        }

        return RedirectToPage();
    }
}

The Index.cshtml file contains the following markup:

<a asp-page="./Edit" asp-route-id="@contact.Id">Edit</a> |

The <a /a> Anchor Tag Helper used the asp-route-{value} attribute to generate a link to the Edit page. The link contains route data with the contact ID. For example, https://localhost:5001/Edit/1. Tag Helpers enable server-side code to participate in creating and rendering HTML elements in Razor files.

The Index.cshtml file contains markup to create a delete button for each customer contact:

<button type="submit" asp-page-handler="delete" asp-route-id="@contact.Id">delete</button>

The rendered HTML:

<button type="submit" formaction="/Customers?id=1&amp;handler=delete">delete</button>

When the delete button is rendered in HTML, its formaction includes parameters for:

• The customer contact ID, specified by the asp-route-id attribute.
• The handler, specified by the asp-page-handler attribute.

When the button is selected, a form POST request is sent to the server. By convention, the name of the handler method is selected based on the value of the handler parameter according to the scheme OnPost[handler]Async.

Because the handler is delete in this example, the OnPostDeleteAsync handler method is used to process the POST request. If the asp-page-handler is set to a different value, such as remove, a handler method with the name OnPostRemoveAsync is selected.

public async Task<IActionResult> OnPostDeleteAsync(int id)
{
    var contact = await _context.Customer.FindAsync(id);

    if (contact != null)
    {
        _context.Customer.Remove(contact);
        await _context.SaveChangesAsync();
    }

    return RedirectToPage();
}

The OnPostDeleteAsync method:

• Gets the id from the query string.
• Queries the database for the customer contact with FindAsync.
• If the customer contact is found, it's removed and the database is updated.
• Calls RedirectToPage to redirect to the root Index page (/Index).

The Edit.cshtml file

@page "{id:int}"
@model RazorPagesContacts.Pages.Customers.EditModel

@{
    ViewData["Title"] = "Edit";
}

<h1>Edit</h1>

<h4>Customer</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        <form method="post">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <input type="hidden" asp-for="Customer!.Id" />
            <div class="form-group">
                <label asp-for="Customer!.Name" class="control-label"></label>
                <input asp-for="Customer!.Name" class="form-control" />
                <span asp-validation-for="Customer!.Name" class="text-danger"></span>
            </div>
            <div class="form-group">
                <input type="submit" value="Save" class="btn btn-primary" />
            </div>
        </form>
    </div>
</div>

<div>
    <a asp-page="./Index">Back to List</a>
</div>

@section Scripts {
    @{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}

The first line contains the @page "{id:int}" directive. The routing constraint "{id:int}" tells the page to accept requests to the page that contain int route data. If a request to the page doesn't contain route data that can be converted to an int, the runtime returns an HTTP 404 (not found) error. To make the ID optional, append ? to the route constraint:

@page "{id:int?}"

The Edit.cshtml.cs file:

public class EditModel : PageModel
{
    private readonly RazorPagesContacts.Data.CustomerDbContext _context;

    public EditModel(RazorPagesContacts.Data.CustomerDbContext context)
    {
        _context = context;
    }

    [BindProperty]
    public Customer? Customer { get; set; }

    public async Task<IActionResult> OnGetAsync(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        Customer = await _context.Customer.FirstOrDefaultAsync(m => m.Id == id);
        
        if (Customer == null)
        {
            return NotFound();
        }
        return Page();
    }

    // To protect from overposting attacks, enable the specific properties you want to bind to.
    // For more details, see https://aka.ms/RazorPagesCRUD.
    public async Task<IActionResult> OnPostAsync()
    {
        if (!ModelState.IsValid)
        {
            return Page();
        }

        if (Customer != null)
        {
            _context.Attach(Customer).State = EntityState.Modified;

            try
            {
                await _context.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!CustomerExists(Customer.Id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }
        }

        return RedirectToPage("./Index");
    }

    private bool CustomerExists(int id)
    {
        return _context.Customer.Any(e => e.Id == id);
    }
}

Validation

Validation rules:

• Are declaratively specified in the model class.
• Are enforced everywhere in the app.

The System.ComponentModel.DataAnnotations namespace provides a set of built-in validation attributes that are applied declaratively to a class or property. DataAnnotations also contains formatting attributes like [DataType] that help with formatting and don't provide any validation.

Consider the Customer model:

using System.ComponentModel.DataAnnotations;

namespace RazorPagesContacts.Models
{
    public class Customer
    {
        public int Id { get; set; }

        [Required, StringLength(10)]
        public string? Name { get; set; }
    }
}

Using the following Create.cshtml view file:

@page
@model RazorPagesContacts.Pages.Customers.CreateModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<p>Validation: customer name:</p>

<form method="post">
    <div asp-validation-summary="ModelOnly"></div>
    <span asp-validation-for="Customer!.Name"></span>
    Name:
    <input asp-for="Customer!.Name" />
    <input type="submit" />
</form>

<script src="~/lib/jquery/dist/jquery.js"></script>
<script src="~/lib/jquery-validation/dist/jquery.validate.js"></script>
<script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js"></script>

The preceding code:

• Includes jQuery and jQuery validation scripts.

• Uses the <div /> and <span /> Tag Helpers to enable:

  • Client-side validation.
  • Validation error rendering.

• Generates the following HTML:

  <p>Enter a customer name:</p>
  
  <form method="post">
      Name:
      <input type="text" data-val="true"
             data-val-length="The field Name must be a string with a maximum length of 10."
             data-val-length-max="10" data-val-required="The Name field is required."
             id="Customer_Name" maxlength="10" name="Customer.Name" value="" />
      <input type="submit" />
      <input name="__RequestVerificationToken" type="hidden"
             value="<Antiforgery token here>" />
  </form>
  
  <script src="/lib/jquery/dist/jquery.js"></script>
  <script src="/lib/jquery-validation/dist/jquery.validate.js"></script>
  <script src="/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js"></script>
  

Posting the Create form without a name value displays the error message "The Name field is required." on the form. If JavaScript is enabled on the client, the browser displays the error without posting to the server.

The [StringLength(10)] attribute generates data-val-length-max="10" on the rendered HTML. data-val-length-max prevents browsers from entering more than the maximum length specified. If a tool such as Fiddler is used to edit and replay the post:

• With the name longer than 10.
• The error message "The field Name must be a string with a maximum length of 10." is returned.

Consider the following Movie model:

using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace RazorPagesMovie.Models
{
    public class Movie
    {
        public int ID { get; set; }

        [StringLength(60, MinimumLength = 3)]
        [Required]
        public string Title { get; set; }

        [Display(Name = "Release Date")]
        [DataType(DataType.Date)]
        public DateTime ReleaseDate { get; set; }

        [Range(1, 100)]
        [DataType(DataType.Currency)]
        [Column(TypeName = "decimal(18, 2)")]
        public decimal Price { get; set; }

        [RegularExpression(@"^[A-Z]+[a-zA-Z\s]*$")]
        [Required]
        [StringLength(30)]
        public string Genre { get; set; }

        [RegularExpression(@"^[A-Z]+[a-zA-Z0-9""'\s-]*$")]
        [StringLength(5)]
        [Required]
        public string Rating { get; set; }
    }
}

The validation attributes specify behavior to enforce on the model properties they're applied to:

• The Required and MinimumLength attributes indicate that a property must have a value, but nothing prevents a user from entering white space to satisfy this validation.

• The RegularExpression attribute is used to limit what characters can be input. In the preceding code, "Genre":

  • Must only use letters.
  • The first letter is required to be uppercase. White space, numbers, and special characters are not allowed.

• The RegularExpression "Rating":

  • Requires that the first character be an uppercase letter.
  • Allows special characters and numbers in subsequent spaces. "PG-13" is valid for a rating, but fails for a "Genre".

• The Range attribute constrains a value to within a specified range.

• The StringLength attribute sets the maximum length of a string property, and optionally its minimum length.

• Value types (such as decimal, int, float, DateTime) are inherently required and don't need the [Required] attribute.

The Create page for the Movie model shows displays errors with invalid values:

For more information, see:

• Add validation to the Movie app
• Model validation in ASP.NET Core.

CSS isolation

Isolate CSS styles to individual pages, views, and components to reduce or avoid:

• Dependencies on global styles that can be challenging to maintain.
• Style conflicts in nested content.

To add a scoped CSS file for a page or view, place the CSS styles in a companion .cshtml.css file matching the name of the .cshtml file. In the following example, an Index.cshtml.css file supplies CSS styles that are only applied to the Index.cshtml page or view.

Pages/Index.cshtml.css (Razor Pages) or Views/Index.cshtml.css (MVC):

h1 {
    color: red;
}

CSS isolation occurs at build time. The framework rewrites CSS selectors to match markup rendered by the app's pages or views. The rewritten CSS styles are bundled and produced as a static asset, {APP ASSEMBLY}.styles.css. The placeholder {APP ASSEMBLY} is the assembly name of the project. A link to the bundled CSS styles is placed in the app's layout.

In the <head> content of the app's Pages/Shared/_Layout.cshtml (Razor Pages) or Views/Shared/_Layout.cshtml (MVC), add or confirm the presence of the link to the bundled CSS styles:

<link rel="stylesheet" href="~/{APP ASSEMBLY}.styles.css" />

In the following example, the app's assembly name is WebApp:

<link rel="stylesheet" href="WebApp.styles.css" />

The styles defined in a scoped CSS file are only applied to the rendered output of the matching file. In the preceding example, any h1 CSS declarations defined elsewhere in the app don't conflict with the Index's heading style. CSS style cascading and inheritance rules remain in effect for scoped CSS files. For example, styles applied directly to an <h1> element in the Index.cshtml file override the scoped CSS file's styles in Index.cshtml.css.

Within the bundled CSS file, each page, view, or Razor component is associated with a scope identifier in the format b-{STRING}, where the {STRING} placeholder is a ten-character string generated by the framework. The following example provides the style for the preceding <h1> element in the Index page of a Razor Pages app:

/* /Pages/Index.cshtml.rz.scp.css */
h1[b-3xxtam6d07] {
    color: red;
}

In the Index page where the CSS style is applied from the bundled file, the scope identifier is appended as an HTML attribute:

<h1 b-3xxtam6d07>

The identifier is unique to an app. At build time, a project bundle is created with the convention {STATIC WEB ASSETS BASE PATH}/Project.lib.scp.css, where the placeholder {STATIC WEB ASSETS BASE PATH} is the static web assets base path.

If other projects are utilized, such as NuGet packages or Razor class libraries, the bundled file:

• References the styles using CSS imports.
• Isn't published as a static web asset of the app that consumes the styles.

CSS preprocessor support

CSS preprocessors are useful for improving CSS development by utilizing features such as variables, nesting, modules, mixins, and inheritance. While CSS isolation doesn't natively support CSS preprocessors such as Sass or Less, integrating CSS preprocessors is seamless as long as preprocessor compilation occurs before the framework rewrites the CSS selectors during the build process. Using Visual Studio for example, configure existing preprocessor compilation as a Before Build task in the Visual Studio Task Runner Explorer.

Many third-party NuGet packages, such as AspNetCore.SassCompiler, can compile SASS/SCSS files at the beginning of the build process before CSS isolation occurs, and no additional configuration is required.

CSS isolation configuration

CSS isolation permits configuration for some advanced scenarios, such as when there are dependencies on existing tools or workflows.

Customize scope identifier format

In this section, the {Pages|Views} placeholder is either Pages for Razor Pages apps or Views for MVC apps.

By default, scope identifiers use the format b-{STRING}, where the {STRING} placeholder is a ten-character string generated by the framework. To customize the scope identifier format, update the project file to a desired pattern:

<ItemGroup>
  <None Update="{Pages|Views}/Index.cshtml.css" CssScope="custom-scope-identifier" />
</ItemGroup>

In the preceding example, the CSS generated for Index.cshtml.css changes its scope identifier from b-{STRING} to custom-scope-identifier.

Use scope identifiers to achieve inheritance with scoped CSS files. In the following project file example, a BaseView.cshtml.css file contains common styles across views. A DerivedView.cshtml.css file inherits these styles.

<ItemGroup>
  <None Update="{Pages|Views}/BaseView.cshtml.css" CssScope="custom-scope-identifier" />
  <None Update="{Pages|Views}/DerivedView.cshtml.css" CssScope="custom-scope-identifier" />
</ItemGroup>

Use the wildcard (*) operator to share scope identifiers across multiple files:

<ItemGroup>
  <None Update="{Pages|Views}/*.cshtml.css" CssScope="custom-scope-identifier" />
</ItemGroup>

Change base path for static web assets

The scoped CSS file is generated at the root of the app. In the project file, use the StaticWebAssetBasePath property to change the default path. The following example places the scoped CSS file, and the rest of the app's assets, at the _content path:

<PropertyGroup>
  <StaticWebAssetBasePath>_content/$(PackageId)</StaticWebAssetBasePath>
</PropertyGroup>

Disable automatic bundling

To opt out of how framework publishes and loads scoped files at runtime, use the DisableScopedCssBundling property. When using this property, other tools or processes are responsible for taking the isolated CSS files from the obj directory and publishing and loading them at runtime:

<PropertyGroup>
  <DisableScopedCssBundling>true</DisableScopedCssBundling>
</PropertyGroup>

Razor class library (RCL) support

When a Razor class library (RCL) provides isolated styles, the <link> tag's href attribute points to {STATIC WEB ASSET BASE PATH}/{PACKAGE ID}.bundle.scp.css, where the placeholders are:

• {STATIC WEB ASSET BASE PATH}: The static web asset base path.
• {PACKAGE ID}: The library's package identifier. The package identifier defaults to the project's assembly name if the package identifier isn't specified in the project file.

In the following example:

• The static web asset base path is _content/ClassLib.
• The class library's assembly name is ClassLib.

Pages/Shared/_Layout.cshtml (Razor Pages) or Views/Shared/_Layout.cshtml (MVC):

<link href="_content/ClassLib/ClassLib.bundle.scp.css" rel="stylesheet">

For more information on RCLs, see the following articles:

• Reusable Razor UI in class libraries with ASP.NET Core
• Consume ASP.NET Core Razor components from a Razor class library (RCL)

For information on Blazor CSS isolation, see ASP.NET Core Blazor CSS isolation.

Handle HEAD requests with an OnGet handler fallback

HEAD requests allow retrieving the headers for a specific resource. Unlike GET requests, HEAD requests don't return a response body.

Ordinarily, an OnHead handler is created and called for HEAD requests:

public void OnHead()
{
    HttpContext.Response.Headers.Add("Head Test", "Handled by OnHead!");
}

Razor Pages falls back to calling the OnGet handler if no OnHead handler is defined.

XSRF/CSRF and Razor Pages

Razor Pages are protected by Antiforgery validation. The FormTagHelper injects antiforgery tokens into HTML form elements.

Using Layouts, partials, templates, and Tag Helpers with Razor Pages

Pages work with all the capabilities of the Razor view engine. Layouts, partials, templates, Tag Helpers, _ViewStart.cshtml, and _ViewImports.cshtml work in the same way they do for conventional Razor views.

Let's declutter this page by taking advantage of some of those capabilities.

Add a layout page to Pages/Shared/_Layout.cshtml:

<!DOCTYPE html>
<html>
<head>
    <title>RP Sample</title>
    <link rel="stylesheet" href="~/lib/bootstrap/dist/css/bootstrap.css" />
</head>
<body>
    <a asp-page="/Index">Home</a>
    <a asp-page="/Customers/Create">Create</a>
    <a asp-page="/Customers/Index">Customers</a> <br />

    @RenderBody()
    <script src="~/lib/jquery/dist/jquery.js"></script>
    <script src="~/lib/jquery-validation/dist/jquery.validate.js"></script>
    <script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js"></script>
</body>
</html>

The Layout:

• Controls the layout of each page (unless the page opts out of layout).
• Imports HTML structures such as JavaScript and stylesheets.
• The contents of the Razor page are rendered where @RenderBody() is called.

For more information, see layout page.

The Layout property is set in Pages/_ViewStart.cshtml:

@{
    Layout = "_Layout";
}

The layout is in the Pages/Shared folder. Pages look for other views (layouts, templates, partials) hierarchically, starting in the same folder as the current page. A layout in the Pages/Shared folder can be used from any Razor page under the Pages folder.

The layout file should go in the Pages/Shared folder.

We recommend you not put the layout file in the Views/Shared folder. Views/Shared is an MVC views pattern. Razor Pages are meant to rely on folder hierarchy, not path conventions.

View search from a Razor Page includes the Pages folder. The layouts, templates, and partials used with MVC controllers and conventional Razor views just work.

Add a Pages/_ViewImports.cshtml file:

@namespace RazorPagesContacts.Pages
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

@namespace is explained later in the tutorial. The @addTagHelper directive brings in the built-in Tag Helpers to all the pages in the Pages folder.

The @namespace directive set on a page:

@page
@namespace RazorPagesIntro.Pages.Customers

@model NameSpaceModel

<h2>Name space</h2>
<p>
    @Model.Message
</p>

The @namespace directive sets the namespace for the page. The @model directive doesn't need to include the namespace.

When the @namespace directive is contained in _ViewImports.cshtml, the specified namespace supplies the prefix for the generated namespace in the Page that imports the @namespace directive. The rest of the generated namespace (the suffix portion) is the dot-separated relative path between the folder containing _ViewImports.cshtml and the folder containing the page.

For example, the PageModel class Pages/Customers/Edit.cshtml.cs explicitly sets the namespace:

namespace RazorPagesContacts.Pages
{
    public class EditModel : PageModel
    {
        private readonly AppDbContext _db;

        public EditModel(AppDbContext db)
        {
            _db = db;
        }

        // Code removed for brevity.

The Pages/_ViewImports.cshtml file sets the following namespace:

@namespace RazorPagesContacts.Pages
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

The generated namespace for the Pages/Customers/Edit.cshtml Razor Page is the same as the PageModel class.

@namespace also works with conventional Razor views.

Consider the Pages/Customers/Create.cshtml view file:

@page
@model RazorPagesContacts.Pages.Customers.CreateModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<p>Validation: customer name:</p>

<form method="post">
    <div asp-validation-summary="ModelOnly"></div>
    <span asp-validation-for="Customer!.Name"></span>
    Name:
    <input asp-for="Customer!.Name" />
    <input type="submit" />
</form>

<script src="~/lib/jquery/dist/jquery.js"></script>
<script src="~/lib/jquery-validation/dist/jquery.validate.js"></script>
<script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js"></script>

The updated Pages/Customers/Create.cshtml view file with _ViewImports.cshtml and the preceding layout file:

@page
@model CreateModel

<p>Enter a customer name:</p>

<form method="post">
    Name:
    <input asp-for="Customer!.Name" />
    <input type="submit" />
</form>

In the preceding code, the _ViewImports.cshtml imported the namespace and Tag Helpers. The layout file imported the JavaScript files.

The Razor Pages starter project contains the Pages/_ValidationScriptsPartial.cshtml, which hooks up client-side validation.

For more information on partial views, see Partial views in ASP.NET Core.

URL generation for Pages

The Create page, shown previously, uses RedirectToPage:

public class CreateModel : PageModel
{
    private readonly Data.CustomerDbContext _context;

    public CreateModel(Data.CustomerDbContext context)
    {
        _context = context;
    }

    public IActionResult OnGet()
    {
        return Page();
    }

    [BindProperty]
    public Customer? Customer { get; set; }

    public async Task<IActionResult> OnPostAsync()
    {
        if (!ModelState.IsValid)
        {
            return Page();
        }

        if (Customer != null) _context.Customer.Add(Customer);
        await _context.SaveChangesAsync();

        return RedirectToPage("./Index");
    }
}

The app has the following file/folder structure:

• /Pages

  • Index.cshtml

  • Privacy.cshtml

  • /Customers

    • Create.cshtml
    • Edit.cshtml
    • Index.cshtml

The Pages/Customers/Create.cshtml and Pages/Customers/Edit.cshtml pages redirect to Pages/Customers/Index.cshtml after success. The string ./Index is a relative page name used to access the preceding page. It is used to generate URLs to the Pages/Customers/Index.cshtml page. For example:

• Url.Page("./Index", ...)
• <a asp-page="./Index">Customers Index Page</a>
• RedirectToPage("./Index")

The absolute page name /Index is used to generate URLs to the Pages/Index.cshtml page. For example:

• Url.Page("/Index", ...)
• <a asp-page="/Index">Home Index Page</a>
• RedirectToPage("/Index")

The page name is the path to the page from the root /Pages folder including a leading / (for example, /Index). The preceding URL generation samples offer enhanced options and functional capabilities over hard-coding a URL. URL generation uses routing and can generate and encode parameters according to how the route is defined in the destination path.

URL generation for pages supports relative names. The following table shows which Index page is selected using different RedirectToPage parameters in Pages/Customers/Create.cshtml.

RedirectToPage("Index"), RedirectToPage("./Index"), and RedirectToPage("../Index") are relative names. The RedirectToPage parameter is combined with the path of the current page to compute the name of the destination page.

Relative name linking is useful when building sites with a complex structure. When relative names are used to link between pages in a folder:

• Renaming a folder doesn't break the relative links.
• Links are not broken because they don't include the folder name.

To redirect to a page in a different Area, specify the area:

RedirectToPage("/Index", new { area = "Services" });

For more information, see Areas in ASP.NET Core and Razor Pages route and app conventions in ASP.NET Core.

ViewData attribute

Data can be passed to a page with ViewDataAttribute. Properties with the [ViewData] attribute have their values stored and loaded from the ViewDataDictionary.

In the following example, the AboutModel applies the [ViewData] attribute to the Title property:

public class AboutModel : PageModel
{
    [ViewData]
    public string Title { get; } = "About";

    public void OnGet()
    {
    }
}

In the About page, access the Title property as a model property:

<h1>@Model.Title</h1>

In the layout, the title is read from the ViewData dictionary:

<!DOCTYPE html>
<html lang="en">
<head>
    <title>@ViewData["Title"] - WebApplication</title>
    ...

TempData

ASP.NET Core exposes the TempData. This property stores data until it's read. The Keep and Peek methods can be used to examine the data without deletion. TempData is useful for redirection, when data is needed for more than a single request.

The following code sets the value of Message using TempData:

public class CreateDotModel : PageModel
{
    private readonly AppDbContext _db;

    public CreateDotModel(AppDbContext db)
    {
        _db = db;
    }

    [TempData]
    public string Message { get; set; }

    [BindProperty]
    public Customer Customer { get; set; }

    public async Task<IActionResult> OnPostAsync()
    {
        if (!ModelState.IsValid)
        {
            return Page();
        }

        _db.Customers.Add(Customer);
        await _db.SaveChangesAsync();
        Message = $"Customer {Customer.Name} added";
        return RedirectToPage("./Index");
    }
}

The following markup in the Pages/Customers/Index.cshtml file displays the value of Message using TempData.

<h3>Msg: @Model.Message</h3>

The Pages/Customers/Index.cshtml.cs page model applies the [TempData] attribute to the Message property.

[TempData]
public string Message { get; set; }

For more information, see TempData.

Multiple handlers per page

The following page generates markup for two handlers using the asp-page-handler Tag Helper:

@page
@model CreateFATHModel

<html>
<body>
    <p>
        Enter your name.
    </p>
    <div asp-validation-summary="All"></div>
    <form method="POST">
        <div>Name: <input asp-for="Customer.Name" /></div>
        <!-- <snippet_Handlers> -->
        <input type="submit" asp-page-handler="JoinList" value="Join" />
        <input type="submit" asp-page-handler="JoinListUC" value="JOIN UC" />
        <!-- </snippet_Handlers> -->
    </form>
</body>
</html>

The form in the preceding example has two submit buttons, each using the FormActionTagHelper to submit to a different URL. The asp-page-handler attribute is a companion to asp-page. asp-page-handler generates URLs that submit to each of the handler methods defined by a page. asp-page isn't specified because the sample is linking to the current page.

The page model:

using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using RazorPagesContacts.Data;

namespace RazorPagesContacts.Pages.Customers
{
    public class CreateFATHModel : PageModel
    {
        private readonly AppDbContext _db;

        public CreateFATHModel(AppDbContext db)
        {
            _db = db;
        }

        [BindProperty]
        public Customer Customer { get; set; }

        public async Task<IActionResult> OnPostJoinListAsync()
        {
            if (!ModelState.IsValid)
            {
                return Page();
            }

            _db.Customers.Add(Customer);
            await _db.SaveChangesAsync();
            return RedirectToPage("/Index");
        }

        public async Task<IActionResult> OnPostJoinListUCAsync()
        {
            if (!ModelState.IsValid)
            {
                return Page();
            }
            Customer.Name = Customer.Name?.ToUpperInvariant();
            return await OnPostJoinListAsync();
        }
    }
}

The preceding code uses named handler methods. Named handler methods are created by taking the text in the name after On<HTTP Verb> and before Async (if present). In the preceding example, the page methods are OnPostJoinListAsync and OnPostJoinListUCAsync. With OnPost and Async removed, the handler names are JoinList and JoinListUC.

<input type="submit" asp-page-handler="JoinList" value="Join" />
<input type="submit" asp-page-handler="JoinListUC" value="JOIN UC" />

Using the preceding code, the URL path that submits to OnPostJoinListAsync is https://localhost:5001/Customers/CreateFATH?handler=JoinList. The URL path that submits to OnPostJoinListUCAsync is https://localhost:5001/Customers/CreateFATH?handler=JoinListUC.

Custom routes

Use the @page directive to:

• Specify a custom route to a page. For example, the route to the About page can be set to /Some/Other/Path with @page "/Some/Other/Path".
• Append segments to a page's default route. For example, an "item" segment can be added to a page's default route with @page "item".
• Append parameters to a page's default route. For example, an ID parameter, id, can be required for a page with @page "{id}".

A root-relative path designated by a tilde (~) at the beginning of the path is supported. For example, @page "~/Some/Other/Path" is the same as @page "/Some/Other/Path".

If you don't like the query string ?handler=JoinList in the URL, change the route to put the handler name in the path portion of the URL. The route can be customized by adding a route template enclosed in double quotes after the @page directive.

@page "{handler?}"
@model CreateRouteModel

<html>
<body>
    <p>
        Enter your name.
    </p>
    <div asp-validation-summary="All"></div>
    <form method="POST">
        <div>Name: <input asp-for="Customer.Name" /></div>
        <input type="submit" asp-page-handler="JoinList" value="Join" />
        <input type="submit" asp-page-handler="JoinListUC" value="JOIN UC" />
    </form>
</body>
</html>

Using the preceding code, the URL path that submits to OnPostJoinListAsync is https://localhost:5001/Customers/CreateFATH/JoinList. The URL path that submits to OnPostJoinListUCAsync is https://localhost:5001/Customers/CreateFATH/JoinListUC.

The ? following handler means the route parameter is optional.

Collocation of JavaScript (JS) files

Collocation of JavaScript (JS) files for pages and views is a convenient way to organize scripts in an app.

Collocate JS files using the following filename extension conventions:

• Pages of Razor Pages apps and views of MVC apps: .cshtml.js. Examples:
  • Pages/Index.cshtml.js for the Index page of a Razor Pages app at Pages/Index.cshtml.
  • Views/Home/Index.cshtml.js for the Index view of an MVC app at Views/Home/Index.cshtml.

Collocated JS files are publicly addressable using the path to the file in the project:

• Pages and views from a collocated scripts file in the app:

  {PATH}/{PAGE, VIEW, OR COMPONENT}.{EXTENSION}.js

  • The {PATH} placeholder is the path to the page, view, or component.
  • The {PAGE, VIEW, OR COMPONENT} placeholder is the page, view, or component.
  • The {EXTENSION} placeholder matches the extension of the page, view, or component, either razor or cshtml.

  Razor Pages example:

  A JS file for the Index page is placed in the Pages folder (Pages/Index.cshtml.js) next to the Index page (Pages/Index.cshtml). In the Index page, the script is referenced at the path in the Pages folder:

  @section Scripts {
    <script src="~/Pages/Index.cshtml.js"></script>
  }
  

  When the app is published, the framework automatically moves the script to the web root. In the preceding example, the script is moved to bin\Release\{TARGET FRAMEWORK MONIKER}\publish\wwwroot\Pages\Index.cshtml.js, where the {TARGET FRAMEWORK MONIKER} placeholder is the Target Framework Moniker (TFM). No change is required to the script's relative URL in the Index page.

  When the app is published, the framework automatically moves the script to the web root. In the preceding example, the script is moved to bin\Release\{TARGET FRAMEWORK MONIKER}\publish\wwwroot\Components\Pages\Index.razor.js, where the {TARGET FRAMEWORK MONIKER} placeholder is the Target Framework Moniker (TFM). No change is required to the script's relative URL in the Index component.

• For scripts provided by a Razor class library (RCL):

  _content/{PACKAGE ID}/{PATH}/{PAGE, VIEW, OR COMPONENT}.{EXTENSION}.js

  • The {PACKAGE ID} placeholder is the RCL's package identifier (or library name for a class library referenced by the app).
  • The {PATH} placeholder is the path to the page, view, or component. If a Razor component is located at the root of the RCL, the path segment isn't included.
  • The {PAGE, VIEW, OR COMPONENT} placeholder is the page, view, or component.
  • The {EXTENSION} placeholder matches the extension of page, view, or component, either razor or cshtml.

Advanced configuration and settings

The configuration and settings in following sections is not required by most apps.

To configure advanced options, use the AddRazorPages overload that configures RazorPagesOptions:

using Microsoft.EntityFrameworkCore;
using RazorPagesContacts.Data;
var builder = WebApplication.CreateBuilder(args);

builder.Services.AddRazorPages(options =>
{
    options.RootDirectory = "/MyPages";
    options.Conventions.AuthorizeFolder("/MyPages/Admin");
});

builder.Services.AddDbContext<CustomerDbContext>(options =>
    options.UseInMemoryDatabase("name"));

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthorization();

app.MapRazorPages();

app.Run();

Use the RazorPagesOptions to set the root directory for pages, or add application model conventions for pages. For more information on conventions, see Razor Pages authorization conventions.

To precompile views, see Razor view compilation.

Specify that Razor Pages are at the content root

By default, Razor Pages are rooted in the /Pages directory. Add WithRazorPagesAtContentRoot to specify that your Razor Pages are at the content root (ContentRootPath) of the app:

using Microsoft.EntityFrameworkCore;
using RazorPagesContacts.Data;
var builder = WebApplication.CreateBuilder(args);

builder.Services.AddRazorPages(options =>
{
    options.Conventions.AuthorizeFolder("/MyPages/Admin");
})
  .WithRazorPagesAtContentRoot();

builder.Services.AddDbContext<CustomerDbContext>(options =>
    options.UseInMemoryDatabase("name"));

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthorization();

app.MapRazorPages();

app.Run();

Specify that Razor Pages are at a custom root directory

Add WithRazorPagesRoot to specify that Razor Pages are at a custom root directory in the app (provide a relative path):

using Microsoft.EntityFrameworkCore;
using RazorPagesContacts.Data;
var builder = WebApplication.CreateBuilder(args);

builder.Services.AddRazorPages(options =>
{
    options.Conventions.AuthorizeFolder("/MyPages/Admin");
})
  .WithRazorPagesRoot("/path/to/razor/pages");

builder.Services.AddDbContext<CustomerDbContext>(options =>
    options.UseInMemoryDatabase("name"));

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error");
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthorization();

app.MapRazorPages();

app.Run();

Additional resources

• See Get started with Razor Pages, which builds on this introduction.
• Authorize attribute and Razor Pages
• Download or view sample code
• Overview of ASP.NET Core
• Razor syntax reference for ASP.NET Core
• Areas in ASP.NET Core
• Tutorial: Get started with Razor Pages in ASP.NET Core
• Razor Pages authorization conventions in ASP.NET Core
• Razor Pages route and app conventions in ASP.NET Core
• Razor Pages unit tests in ASP.NET Core
• Partial views in ASP.NET Core

Create a Razor Pages project

Razor Pages

Razor Pages is enabled in Startup.cs:

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddRazorPages();
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler("/Error");
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.UseStaticFiles();

        app.UseRouting();

        app.UseAuthorization();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapRazorPages();
        });
    }
}

Consider a basic page:

@page

<h1>Hello, world!</h1>
<h2>The time on the server is @DateTime.Now</h2>

The preceding code looks a lot like a Razor view file used in an ASP.NET Core app with controllers and views. What makes it different is the @page directive. @page makes the file into an MVC action - which means that it handles requests directly, without going through a controller. @page must be the first Razor directive on a page. @page affects the behavior of other Razor constructs. Razor Pages file names have a .cshtml suffix.

A similar page, using a PageModel class, is shown in the following two files. The Pages/Index2.cshtml file:

@page
@using RazorPagesIntro.Pages
@model Index2Model

<h2>Separate page model</h2>
<p>
    @Model.Message
</p>

The Pages/Index2.cshtml.cs page model:

using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.Extensions.Logging;
using System;

namespace RazorPagesIntro.Pages
{
    public class Index2Model : PageModel
    {
        public string Message { get; private set; } = "PageModel in C#";

        public void OnGet()
        {
            Message += $" Server time is { DateTime.Now }";
        }
    }
}

By convention, the PageModel class file has the same name as the Razor Page file with .cs appended. For example, the previous Razor Page is Pages/Index2.cshtml. The file containing the PageModel class is named Pages/Index2.cshtml.cs.

The associations of URL paths to pages are determined by the page's location in the file system. The following table shows a Razor Page path and the matching URL:

Notes:

• The runtime looks for Razor Pages files in the Pages folder by default.
• Index is the default page when a URL doesn't include a page.

Write a basic form

Razor Pages is designed to make common patterns used with web browsers easy to implement when building an app. Model binding, Tag Helpers, and HTML helpers all just work with the properties defined in a Razor Page class. Consider a page that implements a basic "contact us" form for the Contact model:

For the samples in this document, the DbContext is initialized in the Startup.cs file.

The in memory database requires the Microsoft.EntityFrameworkCore.InMemory NuGet package.

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<CustomerDbContext>(options =>
                      options.UseInMemoryDatabase("name"));
    services.AddRazorPages();
}

The data model:

using System.ComponentModel.DataAnnotations;

namespace RazorPagesContacts.Models
{
    public class Customer
    {
        public int Id { get; set; }

        [Required, StringLength(10)]
        public string Name { get; set; }
    }
}

The db context:

using Microsoft.EntityFrameworkCore;
using RazorPagesContacts.Models;

namespace RazorPagesContacts.Data
{
    public class CustomerDbContext : DbContext
    {
        public CustomerDbContext(DbContextOptions options)
            : base(options)
        {
        }

        public DbSet<Customer> Customers { get; set; }
    }
}

The Pages/Create.cshtml view file:

@page
@model RazorPagesContacts.Pages.Customers.CreateModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<p>Enter a customer name:</p>

<form method="post">
    Name:
    <input asp-for="Customer.Name" />
    <input type="submit" />
</form>

The Pages/Create.cshtml.cs page model:

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using RazorPagesContacts.Data;
using RazorPagesContacts.Models;
using System.Threading.Tasks;

namespace RazorPagesContacts.Pages.Customers
{
    public class CreateModel : PageModel
    {
        private readonly CustomerDbContext _context;

        public CreateModel(CustomerDbContext context)
        {
            _context = context;
        }

        public IActionResult OnGet()
        {
            return Page();
        }

        [BindProperty]
        public Customer Customer { get; set; }

        public async Task<IActionResult> OnPostAsync()
        {
            if (!ModelState.IsValid)
            {
                return Page();
            }

            _context.Customers.Add(Customer);
            await _context.SaveChangesAsync();

            return RedirectToPage("./Index");
        }
    }
}

By convention, the PageModel class is called <PageName>Model and is in the same namespace as the page.

The PageModel class allows separation of the logic of a page from its presentation. It defines page handlers for requests sent to the page and the data used to render the page. This separation allows:

• Managing of page dependencies through dependency injection.
• Unit testing

The page has an OnPostAsync handler method, which runs on POST requests (when a user posts the form). Handler methods for any HTTP verb can be added. The most common handlers are:

• OnGet to initialize state needed for the page. In the preceding code, the OnGet method displays the CreateModel.cshtml Razor Page.
• OnPost to handle form submissions.

The Async naming suffix is optional but is often used by convention for asynchronous functions. The preceding code is typical for Razor Pages.

If you're familiar with ASP.NET apps using controllers and views:

• The OnPostAsync code in the preceding example looks similar to typical controller code.
• Most of the MVC primitives like model binding, validation, and action results work the same with Controllers and Razor Pages.

The previous OnPostAsync method:

public async Task<IActionResult> OnPostAsync()
{
    if (!ModelState.IsValid)
    {
        return Page();
    }

    _context.Customers.Add(Customer);
    await _context.SaveChangesAsync();

    return RedirectToPage("./Index");
}

The basic flow of OnPostAsync:

Check for validation errors.

• If there are no errors, save the data and redirect.
• If there are errors, show the page again with validation messages. In many cases, validation errors would be detected on the client, and never submitted to the server.

The Pages/Create.cshtml view file:

@page
@model RazorPagesContacts.Pages.Customers.CreateModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<p>Enter a customer name:</p>

<form method="post">
    Name:
    <input asp-for="Customer.Name" />
    <input type="submit" />
</form>

The rendered HTML from Pages/Create.cshtml:

<p>Enter a customer name:</p>

<form method="post">
    Name:
    <input type="text" data-val="true"
           data-val-length="The field Name must be a string with a maximum length of 10."
           data-val-length-max="10" data-val-required="The Name field is required."
           id="Customer_Name" maxlength="10" name="Customer.Name" value="" />
    <input type="submit" />
    <input name="__RequestVerificationToken" type="hidden"
           value="<Antiforgery token here>" />
</form>

In the previous code, posting the form:

• With valid data:

  • The OnPostAsync handler method calls the RedirectToPage helper method. RedirectToPage returns an instance of RedirectToPageResult. RedirectToPage:

    • Is an action result.
    • Is similar to RedirectToAction or RedirectToRoute (used in controllers and views).
    • Is customized for pages. In the preceding sample, it redirects to the root Index page (/Index). RedirectToPage is detailed in the URL generation for Pages section.

• With validation errors that are passed to the server:

  • The OnPostAsync handler method calls the Page helper method. Page returns an instance of PageResult. Returning Page is similar to how actions in controllers return View. PageResult is the default return type for a handler method. A handler method that returns void renders the page.
  • In the preceding example, posting the form with no value results in ModelState.IsValid returning false. In this sample, no validation errors are displayed on the client. Validation error handling is covered later in this document.

  public async Task<IActionResult> OnPostAsync()
  {
      if (!ModelState.IsValid)
      {
          return Page();
      }
  
      _context.Customers.Add(Customer);
      await _context.SaveChangesAsync();
  
      return RedirectToPage("./Index");
  }
  

• With validation errors detected by client side validation:

  • Data is not posted to the server.
  • Client-side validation is explained later in this document.

The Customer property uses [BindProperty] attribute to opt in to model binding:

public class CreateModel : PageModel
{
    private readonly CustomerDbContext _context;

    public CreateModel(CustomerDbContext context)
    {
        _context = context;
    }

    public IActionResult OnGet()
    {
        return Page();
    }

    [BindProperty]
    public Customer Customer { get; set; }

    public async Task<IActionResult> OnPostAsync()
    {
        if (!ModelState.IsValid)
        {
            return Page();
        }

        _context.Customers.Add(Customer);
        await _context.SaveChangesAsync();

        return RedirectToPage("./Index");
    }
}

[BindProperty] should not be used on models containing properties that should not be changed by the client. For more information, see Overposting.

Razor Pages, by default, bind properties only with non-GET verbs. Binding to properties removes the need to writing code to convert HTTP data to the model type. Binding reduces code by using the same property to render form fields (<input asp-for="Customer.Name">) and accept the input.

[BindProperty(SupportsGet = true)]

Reviewing the Pages/Create.cshtml view file:

@page
@model RazorPagesContacts.Pages.Customers.CreateModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<p>Enter a customer name:</p>

<form method="post">
    Name:
    <input asp-for="Customer.Name" />
    <input type="submit" />
</form>

• In the preceding code, the input tag helper <input asp-for="Customer.Name" /> binds the HTML <input> element to the Customer.Name model expression.
• @addTagHelper makes Tag Helpers available.

The home page

Index.cshtml is the home page:

@page
@model RazorPagesContacts.Pages.Customers.IndexModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<h1>Contacts home page</h1>
<form method="post">
    <table class="table">
        <thead>
            <tr>
                <th>ID</th>
                <th>Name</th>
                <th></th>
            </tr>
        </thead>
        <tbody>
            @foreach (var contact in Model.Customer)
            {
                <tr>
                    <td> @contact.Id  </td>
                    <td>@contact.Name</td>
                    <td>
                        <!-- <snippet_Edit> -->
                        <a asp-page="./Edit" asp-route-id="@contact.Id">Edit</a> |
                        <!-- </snippet_Edit> -->
                        <!-- <snippet_Delete> -->
                        <button type="submit" asp-page-handler="delete" asp-route-id="@contact.Id">delete</button>
                        <!-- </snippet_Delete> -->
                    </td>
                </tr>
            }
        </tbody>
    </table>
    <a asp-page="Create">Create New</a>
</form>

The associated PageModel class (Index.cshtml.cs):

public class IndexModel : PageModel
{
    private readonly CustomerDbContext _context;

    public IndexModel(CustomerDbContext context)
    {
        _context = context;
    }

    public IList<Customer> Customer { get; set; }

    public async Task OnGetAsync()
    {
        Customer = await _context.Customers.ToListAsync();
    }

    public async Task<IActionResult> OnPostDeleteAsync(int id)
    {
        var contact = await _context.Customers.FindAsync(id);

        if (contact != null)
        {
            _context.Customers.Remove(contact);
            await _context.SaveChangesAsync();
        }

        return RedirectToPage();
    }
}

The Index.cshtml file contains the following markup:

<a asp-page="./Edit" asp-route-id="@contact.Id">Edit</a> |

The <a /a> Anchor Tag Helper used the asp-route-{value} attribute to generate a link to the Edit page. The link contains route data with the contact ID. For example, https://localhost:5001/Edit/1. Tag Helpers enable server-side code to participate in creating and rendering HTML elements in Razor files.

The Index.cshtml file contains markup to create a delete button for each customer contact:

<button type="submit" asp-page-handler="delete" asp-route-id="@contact.Id">delete</button>

The rendered HTML:

<button type="submit" formaction="/Customers?id=1&amp;handler=delete">delete</button>

When the delete button is rendered in HTML, its formaction includes parameters for:

• The customer contact ID, specified by the asp-route-id attribute.
• The handler, specified by the asp-page-handler attribute.

When the button is selected, a form POST request is sent to the server. By convention, the name of the handler method is selected based on the value of the handler parameter according to the scheme OnPost[handler]Async.

Because the handler is delete in this example, the OnPostDeleteAsync handler method is used to process the POST request. If the asp-page-handler is set to a different value, such as remove, a handler method with the name OnPostRemoveAsync is selected.

public async Task<IActionResult> OnPostDeleteAsync(int id)
{
    var contact = await _context.Customers.FindAsync(id);

    if (contact != null)
    {
        _context.Customers.Remove(contact);
        await _context.SaveChangesAsync();
    }

    return RedirectToPage();
}

The OnPostDeleteAsync method:

• Gets the id from the query string.
• Queries the database for the customer contact with FindAsync.
• If the customer contact is found, it's removed and the database is updated.
• Calls RedirectToPage to redirect to the root Index page (/Index).

The Edit.cshtml file

@page "{id:int}"
@model RazorPagesContacts.Pages.Customers.EditModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers


<h1>Edit Customer - @Model.Customer.Id</h1>
<form method="post">
    <div asp-validation-summary="All"></div>
    <input asp-for="Customer.Id" type="hidden" />
    <div>
        <label asp-for="Customer.Name"></label>
        <div>
            <input asp-for="Customer.Name" />
            <span asp-validation-for="Customer.Name"></span>
        </div>
    </div>

    <div>
        <button type="submit">Save</button>
    </div>
</form>

The first line contains the @page "{id:int}" directive. The routing constraint "{id:int}" tells the page to accept requests to the page that contain int route data. If a request to the page doesn't contain route data that can be converted to an int, the runtime returns an HTTP 404 (not found) error. To make the ID optional, append ? to the route constraint:

@page "{id:int?}"

The Edit.cshtml.cs file:

public class EditModel : PageModel
{
    private readonly CustomerDbContext _context;

    public EditModel(CustomerDbContext context)
    {
        _context = context;
    }

    [BindProperty]
    public Customer Customer { get; set; }

    public async Task<IActionResult> OnGetAsync(int id)
    {
        Customer = await _context.Customers.FindAsync(id);

        if (Customer == null)
        {
            return RedirectToPage("./Index");
        }

        return Page();
    }

    public async Task<IActionResult> OnPostAsync()
    {
        if (!ModelState.IsValid)
        {
            return Page();
        }

        _context.Attach(Customer).State = EntityState.Modified;

        try
        {
            await _context.SaveChangesAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            throw new Exception($"Customer {Customer.Id} not found!");
        }

        return RedirectToPage("./Index");
    }

}

Validation

Validation rules:

• Are declaratively specified in the model class.
• Are enforced everywhere in the app.

The System.ComponentModel.DataAnnotations namespace provides a set of built-in validation attributes that are applied declaratively to a class or property. DataAnnotations also contains formatting attributes like [DataType] that help with formatting and don't provide any validation.

Consider the Customer model:

using System.ComponentModel.DataAnnotations;

namespace RazorPagesContacts.Models
{
    public class Customer
    {
        public int Id { get; set; }

        [Required, StringLength(10)]
        public string Name { get; set; }
    }
}

Using the following Create.cshtml view file:

@page
@model RazorPagesContacts.Pages.Customers.CreateModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<p>Validation: customer name:</p>

<form method="post">
    <div asp-validation-summary="ModelOnly"></div>
    <span asp-validation-for="Customer.Name"></span>
    Name:
    <input asp-for="Customer.Name" />
    <input type="submit" />
</form>

<script src="~/lib/jquery/dist/jquery.js"></script>
<script src="~/lib/jquery-validation/dist/jquery.validate.js"></script>
<script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js"></script>

The preceding code:

• Includes jQuery and jQuery validation scripts.

• Uses the <div /> and <span /> Tag Helpers to enable:

  • Client-side validation.
  • Validation error rendering.

• Generates the following HTML:

  <p>Enter a customer name:</p>
  
  <form method="post">
      Name:
      <input type="text" data-val="true"
             data-val-length="The field Name must be a string with a maximum length of 10."
             data-val-length-max="10" data-val-required="The Name field is required."
             id="Customer_Name" maxlength="10" name="Customer.Name" value="" />
      <input type="submit" />
      <input name="__RequestVerificationToken" type="hidden"
             value="<Antiforgery token here>" />
  </form>
  
  <script src="/lib/jquery/dist/jquery.js"></script>
  <script src="/lib/jquery-validation/dist/jquery.validate.js"></script>
  <script src="/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js"></script>
  

Posting the Create form without a name value displays the error message "The Name field is required." on the form. If JavaScript is enabled on the client, the browser displays the error without posting to the server.

The [StringLength(10)] attribute generates data-val-length-max="10" on the rendered HTML. data-val-length-max prevents browsers from entering more than the maximum length specified. If a tool such as Fiddler is used to edit and replay the post:

• With the name longer than 10.
• The error message "The field Name must be a string with a maximum length of 10." is returned.

Consider the following Movie model:

using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace RazorPagesMovie.Models
{
    public class Movie
    {
        public int ID { get; set; }

        [StringLength(60, MinimumLength = 3)]
        [Required]
        public string Title { get; set; }

        [Display(Name = "Release Date")]
        [DataType(DataType.Date)]
        public DateTime ReleaseDate { get; set; }

        [Range(1, 100)]
        [DataType(DataType.Currency)]
        [Column(TypeName = "decimal(18, 2)")]
        public decimal Price { get; set; }

        [RegularExpression(@"^[A-Z]+[a-zA-Z\s]*$")]
        [Required]
        [StringLength(30)]
        public string Genre { get; set; }

        [RegularExpression(@"^[A-Z]+[a-zA-Z0-9""'\s-]*$")]
        [StringLength(5)]
        [Required]
        public string Rating { get; set; }
    }
}

The validation attributes specify behavior to enforce on the model properties they're applied to:

• The Required and MinimumLength attributes indicate that a property must have a value, but nothing prevents a user from entering white space to satisfy this validation.

• The RegularExpression attribute is used to limit what characters can be input. In the preceding code, "Genre":

  • Must only use letters.
  • The first letter is required to be uppercase. White space, numbers, and special characters are not allowed.

• The RegularExpression "Rating":

  • Requires that the first character be an uppercase letter.
  • Allows special characters and numbers in subsequent spaces. "PG-13" is valid for a rating, but fails for a "Genre".

• The Range attribute constrains a value to within a specified range.

• The StringLength attribute sets the maximum length of a string property, and optionally its minimum length.

• Value types (such as decimal, int, float, DateTime) are inherently required and don't need the [Required] attribute.

The Create page for the Movie model shows displays errors with invalid values:

For more information, see:

• Add validation to the Movie app
• Model validation in ASP.NET Core.

Handle HEAD requests with an OnGet handler fallback

HEAD requests allow retrieving the headers for a specific resource. Unlike GET requests, HEAD requests don't return a response body.

Ordinarily, an OnHead handler is created and called for HEAD requests:

public void OnHead()
{
    HttpContext.Response.Headers.Add("Head Test", "Handled by OnHead!");
}

Razor Pages falls back to calling the OnGet handler if no OnHead handler is defined.

XSRF/CSRF and Razor Pages

Razor Pages are protected by Antiforgery validation. The FormTagHelper injects antiforgery tokens into HTML form elements.

Using Layouts, partials, templates, and Tag Helpers with Razor Pages

Pages work with all the capabilities of the Razor view engine. Layouts, partials, templates, Tag Helpers, _ViewStart.cshtml, and _ViewImports.cshtml work in the same way they do for conventional Razor views.

Let's declutter this page by taking advantage of some of those capabilities.

Add a layout page to Pages/Shared/_Layout.cshtml:

<!DOCTYPE html>
<html>
<head>
    <title>RP Sample</title>
    <link rel="stylesheet" href="~/lib/bootstrap/dist/css/bootstrap.css" />
</head>
<body>
    <a asp-page="/Index">Home</a>
    <a asp-page="/Customers/Create">Create</a>
    <a asp-page="/Customers/Index">Customers</a> <br />

    @RenderBody()
    <script src="~/lib/jquery/dist/jquery.js"></script>
    <script src="~/lib/jquery-validation/dist/jquery.validate.js"></script>
    <script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js"></script>
</body>
</html>

The Layout:

• Controls the layout of each page (unless the page opts out of layout).
• Imports HTML structures such as JavaScript and stylesheets.
• The contents of the Razor page are rendered where @RenderBody() is called.

For more information, see layout page.

The Layout property is set in Pages/_ViewStart.cshtml:

@{
    Layout = "_Layout";
}

The layout is in the Pages/Shared folder. Pages look for other views (layouts, templates, partials) hierarchically, starting in the same folder as the current page. A layout in the Pages/Shared folder can be used from any Razor page under the Pages folder.

The layout file should go in the Pages/Shared folder.

We recommend you not put the layout file in the Views/Shared folder. Views/Shared is an MVC views pattern. Razor Pages are meant to rely on folder hierarchy, not path conventions.

View search from a Razor Page includes the Pages folder. The layouts, templates, and partials used with MVC controllers and conventional Razor views just work.

Add a Pages/_ViewImports.cshtml file:

@namespace RazorPagesContacts.Pages
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

@namespace is explained later in the tutorial. The @addTagHelper directive brings in the built-in Tag Helpers to all the pages in the Pages folder.

The @namespace directive set on a page:

@page
@namespace RazorPagesIntro.Pages.Customers

@model NameSpaceModel

<h2>Name space</h2>
<p>
    @Model.Message
</p>

The @namespace directive sets the namespace for the page. The @model directive doesn't need to include the namespace.

When the @namespace directive is contained in _ViewImports.cshtml, the specified namespace supplies the prefix for the generated namespace in the Page that imports the @namespace directive. The rest of the generated namespace (the suffix portion) is the dot-separated relative path between the folder containing _ViewImports.cshtml and the folder containing the page.

For example, the PageModel class Pages/Customers/Edit.cshtml.cs explicitly sets the namespace:

namespace RazorPagesContacts.Pages
{
    public class EditModel : PageModel
    {
        private readonly AppDbContext _db;

        public EditModel(AppDbContext db)
        {
            _db = db;
        }

        // Code removed for brevity.

The Pages/_ViewImports.cshtml file sets the following namespace:

@namespace RazorPagesContacts.Pages
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

The generated namespace for the Pages/Customers/Edit.cshtml Razor Page is the same as the PageModel class.

@namespace also works with conventional Razor views.

Consider the Pages/Create.cshtml view file:

@page
@model RazorPagesContacts.Pages.Customers.CreateModel
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<p>Validation: customer name:</p>

<form method="post">
    <div asp-validation-summary="ModelOnly"></div>
    <span asp-validation-for="Customer.Name"></span>
    Name:
    <input asp-for="Customer.Name" />
    <input type="submit" />
</form>

<script src="~/lib/jquery/dist/jquery.js"></script>
<script src="~/lib/jquery-validation/dist/jquery.validate.js"></script>
<script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js"></script>

The updated Pages/Create.cshtml view file with _ViewImports.cshtml and the preceding layout file:

@page
@model CreateModel

<p>Enter a customer name:</p>

<form method="post">
    Name:
    <input asp-for="Customer.Name" />
    <input type="submit" />
</form>

In the preceding code, the _ViewImports.cshtml imported the namespace and Tag Helpers. The layout file imported the JavaScript files.

The Razor Pages starter project contains the Pages/_ValidationScriptsPartial.cshtml, which hooks up client-side validation.

For more information on partial views, see Partial views in ASP.NET Core.

URL generation for Pages

The Create page, shown previously, uses RedirectToPage:

public class CreateModel : PageModel
{
    private readonly CustomerDbContext _context;

    public CreateModel(CustomerDbContext context)
    {
        _context = context;
    }

    public IActionResult OnGet()
    {
        return Page();
    }

    [BindProperty]
    public Customer Customer { get; set; }

    public async Task<IActionResult> OnPostAsync()
    {
        if (!ModelState.IsValid)
        {
            return Page();
        }

        _context.Customers.Add(Customer);
        await _context.SaveChangesAsync();

        return RedirectToPage("./Index");
    }
}

The app has the following file/folder structure:

• /Pages

  • Index.cshtml

  • Privacy.cshtml

  • /Customers

    • Create.cshtml
    • Edit.cshtml
    • Index.cshtml

The Pages/Customers/Create.cshtml and Pages/Customers/Edit.cshtml pages redirect to Pages/Customers/Index.cshtml after success. The string ./Index is a relative page name used to access the preceding page. It is used to generate URLs to the Pages/Customers/Index.cshtml page. For example:

• Url.Page("./Index", ...)
• <a asp-page="./Index">Customers Index Page</a>
• RedirectToPage("./Index")

The absolute page name /Index is used to generate URLs to the Pages/Index.cshtml page. For example:

• Url.Page("/Index", ...)
• <a asp-page="/Index">Home Index Page</a>
• RedirectToPage("/Index")

The page name is the path to the page from the root /Pages folder including a leading / (for example, /Index). The preceding URL generation samples offer enhanced options and functional capabilities over hard-coding a URL. URL generation uses routing and can generate and encode parameters according to how the route is defined in the destination path.

URL generation for pages supports relative names. The following table shows which Index page is selected using different RedirectToPage parameters in Pages/Customers/Create.cshtml.

RedirectToPage("Index"), RedirectToPage("./Index"), and RedirectToPage("../Index") are relative names. The RedirectToPage parameter is combined with the path of the current page to compute the name of the destination page.

Relative name linking is useful when building sites with a complex structure. When relative names are used to link between pages in a folder:

• Renaming a folder doesn't break the relative links.
• Links are not broken because they don't include the folder name.

To redirect to a page in a different Area, specify the area:

RedirectToPage("/Index", new { area = "Services" });

For more information, see Areas in ASP.NET Core and Razor Pages route and app conventions in ASP.NET Core.

ViewData attribute

Data can be passed to a page with ViewDataAttribute. Properties with the [ViewData] attribute have their values stored and loaded from the ViewDataDictionary.

In the following example, the AboutModel applies the [ViewData] attribute to the Title property:

public class AboutModel : PageModel
{
    [ViewData]
    public string Title { get; } = "About";

    public void OnGet()
    {
    }
}

In the About page, access the Title property as a model property:

<h1>@Model.Title</h1>

In the layout, the title is read from the ViewData dictionary:

<!DOCTYPE html>
<html lang="en">
<head>
    <title>@ViewData["Title"] - WebApplication</title>
    ...

TempData

ASP.NET Core exposes the TempData. This property stores data until it's read. The Keep and Peek methods can be used to examine the data without deletion. TempData is useful for redirection, when data is needed for more than a single request.

The following code sets the value of Message using TempData:

public class CreateDotModel : PageModel
{
    private readonly AppDbContext _db;

    public CreateDotModel(AppDbContext db)
    {
        _db = db;
    }

    [TempData]
    public string Message { get; set; }

    [BindProperty]
    public Customer Customer { get; set; }

    public async Task<IActionResult> OnPostAsync()
    {
        if (!ModelState.IsValid)
        {
            return Page();
        }

        _db.Customers.Add(Customer);
        await _db.SaveChangesAsync();
        Message = $"Customer {Customer.Name} added";
        return RedirectToPage("./Index");
    }
}

The following markup in the Pages/Customers/Index.cshtml file displays the value of Message using TempData.

<h3>Msg: @Model.Message</h3>

The Pages/Customers/Index.cshtml.cs page model applies the [TempData] attribute to the Message property.

[TempData]
public string Message { get; set; }

For more information, see TempData.

Multiple handlers per page

The following page generates markup for two handlers using the asp-page-handler Tag Helper:

@page
@model CreateFATHModel

<html>
<body>
    <p>
        Enter your name.
    </p>
    <div asp-validation-summary="All"></div>
    <form method="POST">
        <div>Name: <input asp-for="Customer.Name" /></div>
        <!-- <snippet_Handlers> -->
        <input type="submit" asp-page-handler="JoinList" value="Join" />
        <input type="submit" asp-page-handler="JoinListUC" value="JOIN UC" />
        <!-- </snippet_Handlers> -->
    </form>
</body>
</html>

The form in the preceding example has two submit buttons, each using the FormActionTagHelper to submit to a different URL. The asp-page-handler attribute is a companion to asp-page. asp-page-handler generates URLs that submit to each of the handler methods defined by a page. asp-page isn't specified because the sample is linking to the current page.

The page model:

using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using RazorPagesContacts.Data;

namespace RazorPagesContacts.Pages.Customers
{
    public class CreateFATHModel : PageModel
    {
        private readonly AppDbContext _db;

        public CreateFATHModel(AppDbContext db)
        {
            _db = db;
        }

        [BindProperty]
        public Customer Customer { get; set; }

        public async Task<IActionResult> OnPostJoinListAsync()
        {
            if (!ModelState.IsValid)
            {
                return Page();
            }

            _db.Customers.Add(Customer);
            await _db.SaveChangesAsync();
            return RedirectToPage("/Index");
        }

        public async Task<IActionResult> OnPostJoinListUCAsync()
        {
            if (!ModelState.IsValid)
            {
                return Page();
            }
            Customer.Name = Customer.Name?.ToUpperInvariant();
            return await OnPostJoinListAsync();
        }
    }
}

The preceding code uses named handler methods. Named handler methods are created by taking the text in the name after On<HTTP Verb> and before Async (if present). In the preceding example, the page methods are OnPostJoinListAsync and OnPostJoinListUCAsync. With OnPost and Async removed, the handler names are JoinList and JoinListUC.

<input type="submit" asp-page-handler="JoinList" value="Join" />
<input type="submit" asp-page-handler="JoinListUC" value="JOIN UC" />

Using the preceding code, the URL path that submits to OnPostJoinListAsync is https://localhost:5001/Customers/CreateFATH?handler=JoinList. The URL path that submits to OnPostJoinListUCAsync is https://localhost:5001/Customers/CreateFATH?handler=JoinListUC.

Custom routes

Use the @page directive to:

• Specify a custom route to a page. For example, the route to the About page can be set to /Some/Other/Path with @page "/Some/Other/Path".
• Append segments to a page's default route. For example, an "item" segment can be added to a page's default route with @page "item".
• Append parameters to a page's default route. For example, an ID parameter, id, can be required for a page with @page "{id}".

A root-relative path designated by a tilde (~) at the beginning of the path is supported. For example, @page "~/Some/Other/Path" is the same as @page "/Some/Other/Path".

If you don't like the query string ?handler=JoinList in the URL, change the route to put the handler name in the path portion of the URL. The route can be customized by adding a route template enclosed in double quotes after the @page directive.

@page "{handler?}"
@model CreateRouteModel

<html>
<body>
    <p>
        Enter your name.
    </p>
    <div asp-validation-summary="All"></div>
    <form method="POST">
        <div>Name: <input asp-for="Customer.Name" /></div>
        <input type="submit" asp-page-handler="JoinList" value="Join" />
        <input type="submit" asp-page-handler="JoinListUC" value="JOIN UC" />
    </form>
</body>
</html>

Using the preceding code, the URL path that submits to OnPostJoinListAsync is https://localhost:5001/Customers/CreateFATH/JoinList. The URL path that submits to OnPostJoinListUCAsync is https://localhost:5001/Customers/CreateFATH/JoinListUC.

The ? following handler means the route parameter is optional.

Advanced configuration and settings

The configuration and settings in following sections is not required by most apps.

To configure advanced options, use the AddRazorPages overload that configures RazorPagesOptions:

public void ConfigureServices(IServiceCollection services)
{            
    services.AddRazorPages(options =>
    {
        options.RootDirectory = "/MyPages";
        options.Conventions.AuthorizeFolder("/MyPages/Admin");
    });
}

Use the RazorPagesOptions to set the root directory for pages, or add application model conventions for pages. For more information on conventions, see Razor Pages authorization conventions.

To precompile views, see Razor view compilation.

Specify that Razor Pages are at the content root

By default, Razor Pages are rooted in the /Pages directory. Add WithRazorPagesAtContentRoot to specify that your Razor Pages are at the content root (ContentRootPath) of the app:

public void ConfigureServices(IServiceCollection services)
{            
    services.AddRazorPages(options =>
        {
            options.Conventions.AuthorizeFolder("/MyPages/Admin");
        })
        .WithRazorPagesAtContentRoot();
}

Specify that Razor Pages are at a custom root directory

Add WithRazorPagesRoot to specify that Razor Pages are at a custom root directory in the app (provide a relative path):

public void ConfigureServices(IServiceCollection services)
{            
    services.AddRazorPages(options =>
        {
            options.Conventions.AuthorizeFolder("/MyPages/Admin");
        })
        .WithRazorPagesRoot("/path/to/razor/pages");
}

Additional resources

• See Get started with Razor Pages, which builds on this introduction.
• Authorize attribute and Razor Pages
• Download or view sample code
• Overview of ASP.NET Core
• Razor syntax reference for ASP.NET Core
• Areas in ASP.NET Core
• Tutorial: Get started with Razor Pages in ASP.NET Core
• Razor Pages authorization conventions in ASP.NET Core
• Razor Pages route and app conventions in ASP.NET Core
• Razor Pages unit tests in ASP.NET Core
• Partial views in ASP.NET Core