title	author	description	monikerRange	ms.author	ms.custom	ms.date	uid
Integrate ASP.NET Core Razor components into ASP.NET Core apps	guardrex	Learn about Razor component integration scenarios ASP.NET Core apps, Razor Pages and MVC.	>= aspnetcore-8.0	riande	mvc	11/08/2022	blazor/components/integration

Integrate ASP.NET Core Razor components into ASP.NET Core apps

This article explains Razor component integration scenarios for ASP.NET Core apps, including prerendering of Razor components on the server.

Razor components can be integrated into Razor Pages and MVC apps. When the page or view is rendered, components can be prerendered at the same time. Prerendering can improve Search Engine Optimization (SEO) by rendering content for the initial HTTP response that search engines can use to calculate page rank.

Use the guidance in the following sections depending on the project's requirements:

For interactive components that aren't directly routable from user requests, see the Use non-routable components in pages or views section. Follow this guidance when the app embeds components into existing pages and views with the Component Tag Helper.
For interactive components that are directly routable from user requests, see the Use routable components section. Follow this guidance when visitors should be able to make an HTTP request in their browser for a component with an @page directive.

Use non-routable components in pages or views

Use the following guidance to integrate Razor components into pages and views of an existing Razor Pages or MVC app with the Component Tag Helper.

When server prerendering is used and the page or view renders:

The component is prerendered with the page or view.
The initial component state used for prerendering is lost.
New component state is created when the SignalR connection is established.

For more information on rendering modes, including non-interactive static component rendering, see xref:mvc/views/tag-helpers/builtin-th/component-tag-helper. To save the state of prerendered Razor components, see xref:mvc/views/tag-helpers/builtin-th/persist-component-state-tag-helper.

Add a Components folder to the root folder of the project.

Add an imports file to the Components folder with the following content. Change the {APP NAMESPACE} placeholder to the namespace of the project.

Components/_Imports.razor:

@using System.Net.Http
@using System.Net.Http.Json
@using Microsoft.AspNetCore.Components.Forms
@using Microsoft.AspNetCore.Components.Routing
@using Microsoft.AspNetCore.Components.Web
@using Microsoft.AspNetCore.Components.Web.Virtualization
@using Microsoft.JSInterop
@using {APP NAMESPACE}
@using {APP NAMESPACE}.Components

In the project's layout file (Pages/Shared/_Layout.cshtml in Razor Pages apps or Views/Shared/_Layout.cshtml in MVC apps):

Add the following <base> tag and Component Tag Helper for a xref:Microsoft.AspNetCore.Components.Web.HeadOutlet component to the <head> markup:
```
<base href="~/" />
<component type="typeof(Microsoft.AspNetCore.Components.Web.HeadOutlet)" 
    render-mode="ServerPrerendered" />
```
The href value (the app base path) in the preceding example assumes that the app resides at the root URL path (/). If the app is a sub-application, follow the guidance in the App base path section of the xref:blazor/host-and-deploy/index#app-base-path article.

The xref:Microsoft.AspNetCore.Components.Web.HeadOutlet component is used to render head (<head>) content for page titles (xref:Microsoft.AspNetCore.Components.Web.PageTitle component) and other head elements (xref:Microsoft.AspNetCore.Components.Web.HeadContent component) set by Razor components. For more information, see xref:blazor/components/control-head-content.
Add a <script> tag for the blazor.web.js script immediately before the Scripts render section (@await RenderSectionAsync(...)):
```
<script src="_framework/blazor.web.js"></script>
```
There's no need to manually add a blazor.web.js script to the app because the Blazor framework adds the blazor.web.js script to the app.

Note

Typically, the layout loads via a _ViewStart.cshtml file.

Where services are registered, add services for Razor components and services to support rendering interactive server components.

In the Program file before the line that builds the app (builder.Build()):

builder.Services.AddRazorComponents()
    .AddInteractiveServerComponents();

For more information on adding support for server and WebAssembly components, see xref:blazor/components/render-modes.

In the Program file immediately after the call to map Razor Pages (xref:Microsoft.AspNetCore.Builder.RazorPagesEndpointRouteBuilderExtensions.MapRazorPages%2A), call xref:Microsoft.AspNetCore.Builder.RazorComponentsEndpointRouteBuilderExtensions.MapRazorComponents%2A to discover available components and specify the app's root component. By default, the app's root component is the App component (App.razor). Chain a call to AddInteractiveInteractiveServerRenderMode to configure the Server render mode for the app:

app.MapRazorComponents<App>()
    .AddInteractiveServerRenderMode();

Note

If the app hasn't already been updated to include Antiforgery Middleware, add the following line after xref:Microsoft.AspNetCore.Builder.AuthorizationAppBuilderExtensions.UseAuthorization%2A is called:

app.UseAntiforgery();

Integrate components into any page or view. For example, add an EmbeddedCounter component to the project's Components folder.

Components/EmbeddedCounter.razor:

<h1>Embedded Counter</h1>

<p>Current count: @currentCount</p>

<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>

@code {
    private int currentCount = 0;

    private void IncrementCount()
    {
        currentCount++;
    }
}

Razor Pages:

In the project's Index page of a Razor Pages app, add the EmbeddedCounter component's namespace and embed the component into the page. When the Index page loads, the EmbeddedCounter component is prerendered in the page. In the following example, replace the {APP NAMESPACE} placeholder with the project's namespace.

Pages/Index.cshtml:

@page
@using {APP NAMESPACE}.Components
@model IndexModel
@{
    ViewData["Title"] = "Home page";
}

<component type="typeof(EmbeddedCounter)" render-mode="ServerPrerendered" />

MVC:

In the project's Index view of an MVC app, add the EmbeddedCounter component's namespace and embed the component into the view. When the Index view loads, the EmbeddedCounter component is prerendered in the page. In the following example, replace the {APP NAMESPACE} placeholder with the project's namespace.

Views/Home/Index.cshtml:

@using {APP NAMESPACE}.Components
@{
    ViewData["Title"] = "Home Page";
}

<component type="typeof(EmbeddedCounter)" render-mode="ServerPrerendered" />

Use routable components

Use the following guidance to integrate routable Razor components into an existing Razor Pages or MVC app.

The guidance in this section assumes:

The title of the app is Blazor Sample.
The namespace of the app is BlazorSample.

To support routable Razor components:

Add a Components folder to the root folder of the project.

Add an imports file to the Components folder with the following content.

Components/_Imports.razor:

@using System.Net.Http
@using System.Net.Http.Json
@using Microsoft.AspNetCore.Components.Forms
@using Microsoft.AspNetCore.Components.Routing
@using Microsoft.AspNetCore.Components.Web
@using Microsoft.AspNetCore.Components.Web.Virtualization
@using Microsoft.JSInterop
@using {APP NAMESPACE}
@using {APP NAMESPACE}.Components

Change the {APP NAMESPACE} placeholder to the namespace of the project. For example:

@using BlazorSample
@using BlazorSample.Components

Add a Layout folder to the Components folder.

Add a footer component and stylesheet to the Layout folder.

Components/Layout/Footer.razor:

<footer class="border-top footer text-muted">
    <div class="container">
        &copy; 2023 - {APP TITLE} - <a href="/privacy">Privacy</a>
    </div>
</footer>

In the preceding markup, set the {APP TITLE} placeholder to the title of the app. For example:

&copy; 2023 - Blazor Sample - <a href="/privacy">Privacy</a>

Components/Layout/Footer.razor.css:

.footer {
position: absolute;
bottom: 0;
width: 100%;
white-space: nowrap;
line-height: 60px;
}

Add a navigation menu component to the Layout folder.

Components/Layout/NavMenu.razor:

<nav class="navbar navbar-expand-sm navbar-toggleable-sm navbar-light bg-white border-bottom box-shadow mb-3">
<div class="container">
    <a class="navbar-brand" href="/">{APP TITLE}</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target=".navbar-collapse" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
        <span class="navbar-toggler-icon"></span>
    </button>
    <div class="navbar-collapse collapse d-sm-inline-flex justify-content-between">
        <ul class="navbar-nav flex-grow-1">
            <li class="nav-item">
                <a class="nav-link text-dark" href="/">Home</a>
            </li>
            <li class="nav-item">
                <a class="nav-link text-dark" href="/privacy">Privacy</a>
            </li>
            <li class="nav-item">
                <a class="nav-link text-dark" href="/counter">Counter</a>
            </li>
        </ul>
    </div>
</div>
</nav>

In the preceding markup, set the {APP TITLE} placeholder to the title of the app. For example:

<a class="navbar-brand" href="/">Blazor Sample</a>

Components/Layout/NavMenu.razor.css:

a.navbar-brand {
    white-space: normal;
    text-align: center;
    word-break: break-all;
}

a {
    color: #0077cc;
}

.btn-primary {
    color: #fff;
    background-color: #1b6ec2;
    border-color: #1861ac;
}

.nav-pills .nav-link.active, .nav-pills .show > .nav-link {
    color: #fff;
    background-color: #1b6ec2;
    border-color: #1861ac;
}

.border-top {
    border-top: 1px solid #e5e5e5;
}

.border-bottom {
    border-bottom: 1px solid #e5e5e5;
}

.box-shadow {
    box-shadow: 0 .25rem .75rem rgba(0, 0, 0, .05);
}

button.accept-policy {
    font-size: 1rem;
    line-height: inherit;
}

Add a main layout component and stylesheet to the Layout folder.

Components/Layout/MainLayout.razor:

@inherits LayoutComponentBase

<header>
    <NavMenu />
</header>

<div class="container">
    <main role="main" class="pb-3">
        @Body
    </main>
</div>

<Footer />

<div id="blazor-error-ui">
    An unhandled error has occurred.
    <a href="" class="reload">Reload</a>
    <a class="dismiss">🗙</a>
</div>

Components/Layout/MainLayout.razor.css:

#blazor-error-ui {
    background: lightyellow;
    bottom: 0;
    box-shadow: 0 -1px 2px rgba(0, 0, 0, 0.2);
    display: none;
    left: 0;
    padding: 0.6rem 1.25rem 0.7rem 1.25rem;
    position: fixed;
    width: 100%;
    z-index: 1000;
}

    #blazor-error-ui .dismiss {
        cursor: pointer;
        position: absolute;
        right: 0.75rem;
        top: 0.5rem;
    }

Add a Routes component to the Components folder with the following content.

Components/Routes.razor:

<Router AppAssembly="@typeof(Program).Assembly">
    <Found Context="routeData">
        <RouteView RouteData="@routeData" DefaultLayout="@typeof(Layout.MainLayout)" />
        <FocusOnNavigate RouteData="@routeData" Selector="h1" />
    </Found>
</Router>

Add an App component to the Components folder with the following content.

Components/App.razor:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>{APP TITLE}</title>
    <link rel="stylesheet" href="/lib/bootstrap/dist/css/bootstrap.min.css" />
    <link rel="stylesheet" href="/css/site.css" />
    <link rel="stylesheet" href="/{APP NAMESPACE}.styles.css" />
    <HeadOutlet />
</head>
<body>
    <Routes />
    <script src="/lib/jquery/dist/jquery.min.js"></script>
    <script src="/lib/bootstrap/dist/js/bootstrap.bundle.min.js"></script>
    <script src="/js/site.js"></script>
    <script src="_framework/blazor.web.js"></script>
</body>
</html>

In the preceding code update the app title and stylesheet file name:

For the {APP TITLE} placeholder in the <title> element, set the app's title. For example:
```
<title>Blazor Sample</title>
```
For the {APP NAMESPACE} placeholder in the stylesheet <link> element, set the app's namespace. For example:
```
<link rel="stylesheet" href="/BlazorSample.styles.css" />
```

Where services are registered, add services for Razor components and services to support rendering interactive server components.

In the Program file before the line that builds the app (builder.Build()):

builder.Services.AddRazorComponents()
    .AddInteractiveServerComponents();

For more information on adding support for server and WebAssembly components, see xref:blazor/components/render-modes.

In the Program file immediately after the call to map Razor Pages (xref:Microsoft.AspNetCore.Builder.RazorPagesEndpointRouteBuilderExtensions.MapRazorPages%2A), call xref:Microsoft.AspNetCore.Builder.RazorComponentsEndpointRouteBuilderExtensions.MapRazorComponents%2A to discover available components and specify the app's root component. By default, the app's root component is the App component (App.razor). Chain a call to AddInteractiveInteractiveServerRenderMode to configure the Server render mode for the app:

app.MapRazorComponents<App>()
    .AddInteractiveServerRenderMode();

Note

If the app hasn't already been updated to include Antiforgery Middleware, add the following line after xref:Microsoft.AspNetCore.Builder.AuthorizationAppBuilderExtensions.UseAuthorization%2A is called:

app.UseAntiforgery();

Create a Pages folder in the Components folder for routable components. The following example is a Counter component based on the Counter component in the Blazor project templates.

Components/Pages/Counter.razor:

@page "/counter"
@rendermode RenderMode.InteractiveServer

<PageTitle>Counter</PageTitle>

<h1>Counter</h1>

<p>Current count: @currentCount</p>

<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>

@code {
    private int currentCount = 0;

    private void IncrementCount()
    {
        currentCount++;
    }
}

Run the project and navigate to the routable Counter component at /counter.

For more information on namespaces, see the Component namespaces section.

Return a `RazorComponentResult` from an MVC controller action

An MVC controller action can return a component with RazorComponentResult.

Components/Welcome.razor:

<PageTitle>Welcome!</PageTitle>

<h1>Welcome!</h1>

<p>@Message</p>

@code {
    [Parameter]
    public string? Message { get; set; }
}

In a controller:

public IResult GetWelcomeComponent()
{
    return new RazorComponentResult<Welcome>(new { Message = "Hello, world!" });
}

Component namespaces

When using a custom folder to hold the project's Razor components, add the namespace representing the folder to either the page/view or to the _ViewImports.cshtml file. In the following example:

Components are stored in the Components folder of the project.
The {APP NAMESPACE} placeholder is the project's namespace. Components represents the name of the folder.

@using {APP NAMESPACE}.Components

For example:

@using BlazorSample.Components

The _ViewImports.cshtml file is located in the Pages folder of a Razor Pages app or the Views folder of an MVC app.

For more information, see xref:blazor/components/index#class-name-and-namespace.

Additional resources

xref:blazor/components/prerender

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integration.md

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Integrate ASP.NET Core Razor components into ASP.NET Core apps

Use non-routable components in pages or views

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Return a `RazorComponentResult` from an MVC controller action

Component namespaces

Additional resources

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Integrate ASP.NET Core Razor components into ASP.NET Core apps

Use non-routable components in pages or views

Use routable components

Return a RazorComponentResult from an MVC controller action

Component namespaces

Additional resources

Return a `RazorComponentResult` from an MVC controller action