ASP.NET Core Blazor dependency injection

By Rainer Stropek and Mike Rousos

This article explains how Blazor apps can inject services into components.

Dependency injection (DI) is a technique for accessing services configured in a central location:

• Framework-registered services can be injected directly into Razor components.
• Blazor apps define and register custom services and make them available throughout the app via DI.

Note

We recommend reading Dependency injection in ASP.NET Core before reading this topic.

Throughout this article, the terms client/client-side and server/server-side are used to distinguish locations where app code executes:

• Client/client-side
  • Client-side rendering (CSR) of a Blazor Web App. The Program file is Program.cs of the client project (.Client). Blazor script start configuration is found in the App component (Components/App.razor) of the server project. Routable Interactive WebAssembly and Interactive Auto render mode components with an @page directive are placed in the client project's Pages folder. Place non-routable shared components at the root of the .Client project or in custom folders based on component functionality.
  • A Blazor WebAssembly app. The Program file is Program.cs. Blazor script start configuration is found in the wwwroot/index.html file.
• Server/server-side: Interactive server-side rendering (interactive SSR) of a Blazor Web App. The Program file is Program.cs of the server project. Blazor script start configuration is found in the App component (Components/App.razor). Only routable Interactive Server render mode components with an @page directive are placed in the Components/Pages folder. Non-routable shared components are placed in the server project's Components folder. Create custom folders based on component functionality as needed.

Default services

The services shown in the following table are commonly used in Blazor apps.

Service	Lifetime	Description
HttpClient	Scoped	Provides methods for sending HTTP requests and receiving HTTP responses from a resource identified by a URI. Client-side, an instance of HttpClient is registered by the app in the Program file and uses the browser for handling the HTTP traffic in the background. Server-side, an HttpClient isn't configured as a service by default. In server-side code, provide an HttpClient. For more information, see Call a web API from an ASP.NET Core Blazor app. An HttpClient is registered as a scoped service, not singleton. For more information, see the Service lifetime section.
IJSRuntime	Client-side: Singleton Server-side: Scoped The Blazor framework registers IJSRuntime in the app's service container.	Represents an instance of a JavaScript runtime where JavaScript calls are dispatched. For more information, see Call JavaScript functions from .NET methods in ASP.NET Core Blazor. When seeking to inject the service into a singleton service on the server, take either of the following approaches: Change the service registration to scoped to match IJSRuntime's registration, which is appropriate if the service deals with user-specific state. Pass the IJSRuntime into the singleton service's implementation as an argument of its method calls instead of injecting it into the singleton.
NavigationManager	Client-side: Singleton Server-side: Scoped The Blazor framework registers NavigationManager in the app's service container.	Contains helpers for working with URIs and navigation state. For more information, see URI and navigation state helpers.

Additional services registered by the Blazor framework are described in the documentation where they're used to describe Blazor features, such as configuration and logging.

A custom service provider doesn't automatically provide the default services listed in the table. If you use a custom service provider and require any of the services shown in the table, add the required services to the new service provider.

Add client-side services

Configure services for the app's service collection in the Program file. In the following example, the ExampleDependency implementation is registered for IExampleDependency:

var builder = WebAssemblyHostBuilder.CreateDefault(args);
...
builder.Services.AddSingleton<IExampleDependency, ExampleDependency>();
...

await builder.Build().RunAsync();

After the host is built, services are available from the root DI scope before any components are rendered. This can be useful for running initialization logic before rendering content:

var builder = WebAssemblyHostBuilder.CreateDefault(args);
...
builder.Services.AddSingleton<WeatherService>();
...

var host = builder.Build();

var weatherService = host.Services.GetRequiredService<WeatherService>();
await weatherService.InitializeWeatherAsync();

await host.RunAsync();

The host provides a central configuration instance for the app. Building on the preceding example, the weather service's URL is passed from a default configuration source (for example, appsettings.json) to InitializeWeatherAsync:

var builder = WebAssemblyHostBuilder.CreateDefault(args);
...
builder.Services.AddSingleton<WeatherService>();
...

var host = builder.Build();

var weatherService = host.Services.GetRequiredService<WeatherService>();
await weatherService.InitializeWeatherAsync(
    host.Configuration["WeatherServiceUrl"]);

await host.RunAsync();

Add server-side services

After creating a new app, examine part of the Program file:

var builder = WebApplication.CreateBuilder(args);

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

The builder variable represents a WebApplicationBuilder with an IServiceCollection, which is a list of service descriptor objects. Services are added by providing service descriptors to the service collection. The following example demonstrates the concept with the IDataAccess interface and its concrete implementation DataAccess:

builder.Services.AddSingleton<IDataAccess, DataAccess>();

Register common services

If one or more common services are required client- and server-side, you can place the common service registrations in a method client-side and call the method to register the services in both projects.

First, factor common service registrations into a separate method. For example, create a ConfigureCommonServices method client-side:

public static void ConfigureCommonServices(IServiceCollection services)
{
    services.Add...;
}

For the client-side Program file, call ConfigureCommonServices to register the common services:

var builder = WebAssemblyHostBuilder.CreateDefault(args);

...

ConfigureCommonServices(builder.Services);

In the server-side Program file, call ConfigureCommonServices to register the common services:

var builder = WebApplication.CreateBuilder(args);

...

Client.Program.ConfigureCommonServices(builder.Services);

For an example of this approach, see ASP.NET Core Blazor WebAssembly additional security scenarios.

Service lifetime

Services can be configured with the lifetimes shown in the following table.

Lifetime	Description
Scoped	Client-side doesn't currently have a concept of DI scopes. Scoped-registered services behave like Singleton services. Server-side development supports the Scoped lifetime across HTTP requests but not across SignalR connection/circuit messages among components that are loaded on the client. The Razor Pages or MVC portion of the app treats scoped services normally and recreates the services on each HTTP request when navigating among pages or views or from a page or view to a component. Scoped services aren't reconstructed when navigating among components on the client, where the communication to the server takes place over the SignalR connection of the user's circuit, not via HTTP requests. In the following component scenarios on the client, scoped services are reconstructed because a new circuit is created for the user: The user closes the browser's window. The user opens a new window and navigates back to the app. The user closes a tab of the app in a browser window. The user opens a new tab and navigates back to the app. The user selects the browser's reload/refresh button. For more information on preserving user state in server-side apps, see ASP.NET Core Blazor state management.
Singleton	DI creates a single instance of the service. All components requiring a Singleton service receive the same instance of the service.
Transient	Whenever a component obtains an instance of a Transient service from the service container, it receives a new instance of the service.

The DI system is based on the DI system in ASP.NET Core. For more information, see Dependency injection in ASP.NET Core.

Request a service in a component

After services are added to the service collection, inject the services into the components using the @inject Razor directive, which has two parameters:

• Type: The type of the service to inject.
• Property: The name of the property receiving the injected app service. The property doesn't require manual creation. The compiler creates the property.

For more information, see Dependency injection into views in ASP.NET Core.

Use multiple @inject statements to inject different services.

The following example shows how to use @inject. The service implementing Services.IDataAccess is injected into the component's property DataRepository. Note how the code is only using the IDataAccess abstraction:

@page "/customer-list"
@inject IDataAccess DataRepository

@if (customers != null)
{
    <ul>
        @foreach (var customer in customers)
        {
            <li>@customer.FirstName @customer.LastName</li>
        }
    </ul>
}

@code {
    private IReadOnlyList<Customer>? customers;

    protected override async Task OnInitializedAsync()
    {
        customers = await DataRepository.GetAllCustomersAsync();
    }

    private class Customer
    {
        public string? FirstName { get; set; }
        public string? LastName { get; set; }
    }

    private interface IDataAccess
    {
        public Task<IReadOnlyList<Customer>> GetAllCustomersAsync();
    }
}

Internally, the generated property (DataRepository) uses the [Inject] attribute. Typically, this attribute isn't used directly. If a base class is required for components and injected properties are also required for the base class, manually add the [Inject] attribute:

using Microsoft.AspNetCore.Components;

public class ComponentBase : IComponent
{
    [Inject]
    protected IDataAccess DataRepository { get; set; } = default!;

    ...
}

Note

Since injected services are expected to be available, the default literal with the null-forgiving operator (default!) is assigned in .NET 6 or later. For more information, see Nullable reference types (NRTs) and .NET compiler null-state static analysis.

In components derived from the base class, the @inject directive isn't required. The InjectAttribute of the base class is sufficient:

@page "/demo"
@inherits ComponentBase

<h1>Demo Component</h1>

Use DI in services

Complex services might require additional services. In the following example, DataAccess requires the HttpClient default service. @inject (or the [Inject] attribute) isn't available for use in services. Constructor injection must be used instead. Required services are added by adding parameters to the service's constructor. When DI creates the service, it recognizes the services it requires in the constructor and provides them accordingly. In the following example, the constructor receives an HttpClient via DI. HttpClient is a default service.

using System.Net.Http;

public class DataAccess : IDataAccess
{
    public DataAccess(HttpClient http)
    {
        ...
    }
}

Prerequisites for constructor injection:

• One constructor must exist whose arguments can all be fulfilled by DI. Additional parameters not covered by DI are allowed if they specify default values.
• The applicable constructor must be public.
• One applicable constructor must exist. In case of an ambiguity, DI throws an exception.

Inject keyed services into components

Blazor supports injecting keyed services using the [Inject] attribute. Keys allow for scoping of registration and consumption of services when using dependency injection. Use the InjectAttribute.Key property to specify the key for the service to inject:

[Inject(Key = "my-service")]
public IMyService MyService { get; set; }

Utility base component classes to manage a DI scope

In ASP.NET Core apps, scoped services are typically scoped to the current request. After the request completes, any scoped or transient services are disposed by the DI system. Server-side, the request scope lasts for the duration of the client connection, which can result in transient and scoped services living much longer than expected. Client-side, services registered with a scoped lifetime are treated as singletons, so they live longer than scoped services in typical ASP.NET Core apps.

Note

To detect disposable transient services in an app, see the following sections:

Detect client-side transient disposables Detect server-side transient disposables

An approach that limits a service lifetime is use of the OwningComponentBase type. OwningComponentBase is an abstract type derived from ComponentBase that creates a DI scope corresponding to the lifetime of the component. Using this scope, it's possible to use DI services with a scoped lifetime and have them live as long as the component. When the component is destroyed, services from the component's scoped service provider are disposed as well. This can be useful for services that:

• Should be reused within a component, as the transient lifetime is inappropriate.
• Shouldn't be shared across components, as the singleton lifetime is inappropriate.

Two versions of OwningComponentBase type are available and described in the next two sections:

• OwningComponentBase
• OwningComponentBase<TService>

OwningComponentBase

OwningComponentBase is an abstract, disposable child of the ComponentBase type with a protected ScopedServices property of type IServiceProvider. The provider can be used to resolve services that are scoped to the lifetime of the component.

DI services injected into the component using @inject or the [Inject] attribute aren't created in the component's scope. To use the component's scope, services must be resolved using ScopedServices with either GetRequiredService or GetService. Any services resolved using the ScopedServices provider have their dependencies provided in the component's scope.

The following example demonstrates the difference between injecting a scoped service directly and resolving a service using ScopedServices on the server. The following interface and implementation for a time travel class include a DT property to hold a DateTime value. The implementation calls DateTime.Now to set DT when the TimeTravel class is instantiated.

ITimeTravel.cs:

public interface ITimeTravel
{
    public DateTime DT { get; set; }
}

TimeTravel.cs:

public class TimeTravel : ITimeTravel
{
    public DateTime DT { get; set; } = DateTime.Now;
}

The service is registered as scoped in the server-side Program file. Server-side, scoped services have a lifetime equal to the duration of the circuit.

In the Program file:

builder.Services.AddScoped<ITimeTravel, TimeTravel>();

In the following TimeTravel component:

• The time travel service is directly injected with @inject as TimeTravel1.
• The service is also resolved separately with ScopedServices and GetRequiredService as TimeTravel2.

TimeTravel.razor:

@page "/time-travel"
@rendermode InteractiveServer
@inject ITimeTravel TimeTravel1
@inherits OwningComponentBase

<h1><code>OwningComponentBase</code> Example</h1>

<ul>
    <li>TimeTravel1.DT: @TimeTravel1?.DT</li>
    <li>TimeTravel2.DT: @TimeTravel2?.DT</li>
</ul>

@code {
    private ITimeTravel TimeTravel2 { get; set; } = default!;

    protected override void OnInitialized()
    {
        TimeTravel2 = ScopedServices.GetRequiredService<ITimeTravel>();
    }
}

Initially navigating to the TimeTravel component, the time travel service is instantiated twice when the component loads, and TimeTravel1 and TimeTravel2 have the same initial value:

TimeTravel1.DT: 8/31/2022 2:54:45 PM
TimeTravel2.DT: 8/31/2022 2:54:45 PM

When navigating away from the TimeTravel component to another component and back to the TimeTravel component:

• TimeTravel1 is provided the same service instance that was created when the component first loaded, so the value of DT remains the same.
• TimeTravel2 obtains a new ITimeTravel service instance in TimeTravel2 with a new DT value.

TimeTravel1.DT: 8/31/2022 2:54:45 PM
TimeTravel2.DT: 8/31/2022 2:54:48 PM

TimeTravel1 is tied to the user's circuit, which remains intact and isn't disposed until the underlying circuit is deconstructed. For example, the service is disposed if the circuit is disconnected for the disconnected circuit retention period.

In spite of the scoped service registration in the Program file and the longevity of the user's circuit, TimeTravel2 receives a new ITimeTravel service instance each time the component is initialized.

OwningComponentBase<TService>

OwningComponentBase<TService> derives from OwningComponentBase and adds a Service property that returns an instance of T from the scoped DI provider. This type is a convenient way to access scoped services without using an instance of IServiceProvider when there's one primary service the app requires from the DI container using the component's scope. The ScopedServices property is available, so the app can get services of other types, if necessary.

@page "/users"
@rendermode InteractiveServer
@attribute [Authorize]
@inherits OwningComponentBase<AppDbContext>

<h1>Users (@Service.Users.Count())</h1>

<ul>
    @foreach (var user in Service.Users)
    {
        <li>@user.UserName</li>
    }
</ul>

Use of an Entity Framework Core (EF Core) DbContext from DI

For more information, see ASP.NET Core Blazor with Entity Framework Core (EF Core).

Detect client-side transient disposables

The following Blazor WebAssembly example shows how to detect client-side disposable transient services in an app that should use OwningComponentBase. For more information, see the Utility base component classes to manage a DI scope section.

DetectIncorrectUsagesOfTransientDisposables.cs for client-side development:

using Microsoft.Extensions.DependencyInjection.Extensions;

namespace Microsoft.Extensions.DependencyInjection
{
    using BlazorWebAssemblyTransientDisposable;
    using Microsoft.AspNetCore.Components.WebAssembly.Hosting;

    public static class WebHostBuilderTransientDisposableExtensions
    {
        public static WebAssemblyHostBuilder DetectIncorrectUsageOfTransients(
            this WebAssemblyHostBuilder builder)
        {
            builder
                .ConfigureContainer(
                    new DetectIncorrectUsageOfTransientDisposablesServiceFactory());

            return builder;
        }

        public static WebAssemblyHost EnableTransientDisposableDetection(
            this WebAssemblyHost webAssemblyHost)
        {
            webAssemblyHost.Services
                .GetRequiredService<ThrowOnTransientDisposable>().ShouldThrow = true;

            return webAssemblyHost;
        }
    }
}

namespace BlazorWebAssemblyTransientDisposable
{
    public class DetectIncorrectUsageOfTransientDisposablesServiceFactory 
        : IServiceProviderFactory<IServiceCollection>
    {
        public IServiceCollection CreateBuilder(IServiceCollection services) => 
            services;

        public IServiceProvider CreateServiceProvider(
            IServiceCollection containerBuilder)
        {
            var collection = new ServiceCollection();

            foreach (var descriptor in containerBuilder)
            {
                if (descriptor.Lifetime == ServiceLifetime.Transient &&
                    descriptor.ImplementationType != null && 
                    typeof(IDisposable).IsAssignableFrom(
                        descriptor.ImplementationType))
                {
                    collection.Add(CreatePatchedDescriptor(descriptor));
                }
                else if (descriptor.Lifetime == ServiceLifetime.Transient &&
                         descriptor.ImplementationFactory != null)
                {
                    collection.Add(CreatePatchedFactoryDescriptor(descriptor));
                }
                else
                {
                    collection.Add(descriptor);
                }
            }

            collection.AddScoped<ThrowOnTransientDisposable>();

            return collection.BuildServiceProvider();
        }

        private ServiceDescriptor CreatePatchedFactoryDescriptor(
            ServiceDescriptor original)
        {
            var newDescriptor = new ServiceDescriptor(
                original.ServiceType,
                (sp) =>
                {
                    var originalFactory = original.ImplementationFactory;
                    
                    if (originalFactory is null)
                    {
                        throw new InvalidOperationException(
                            "originalFactory is null.");
                    }

                    var originalResult = originalFactory(sp);

                    var throwOnTransientDisposable = 
                        sp.GetRequiredService<ThrowOnTransientDisposable>();
                    if (throwOnTransientDisposable.ShouldThrow && 
                        originalResult is IDisposable d)
                    {
                        throw new InvalidOperationException("Trying to resolve " +
                            $"transient disposable service {d.GetType().Name} in " +
                            "the wrong scope. Use an 'OwningComponentBase<T>' " +
                            "component base class for the service 'T' you are " +
                            "trying to resolve.");
                    }

                    return originalResult;
                },
                original.Lifetime);

            return newDescriptor;
        }

        private ServiceDescriptor CreatePatchedDescriptor(ServiceDescriptor original)
        {
            var newDescriptor = new ServiceDescriptor(
                original.ServiceType,
                (sp) => {
                    var throwOnTransientDisposable = 
                        sp.GetRequiredService<ThrowOnTransientDisposable>();
                    if (throwOnTransientDisposable.ShouldThrow)
                    {
                        throw new InvalidOperationException("Trying to resolve " +
                        "transient disposable service " +
                        $"{original.ImplementationType?.Name} in the wrong " +
                        "scope. Use an 'OwningComponentBase<T>' component base " +
                        "class for the service 'T' you are trying to resolve.");
                    }

                    if (original.ImplementationType is null)
                    {
                        throw new InvalidOperationException(
                            "ImplementationType is null.");
                    }

                    return ActivatorUtilities.CreateInstance(sp, 
                        original.ImplementationType);
                },
                ServiceLifetime.Transient);
    
            return newDescriptor;
        }
    }

    internal class ThrowOnTransientDisposable
    {
        public bool ShouldThrow { get; set; }
    }
}

TransientDisposable.cs:

public class TransientDisposable : IDisposable
{
    public void Dispose() => throw new NotImplementedException();
}

The TransientDisposable in the following example is detected.

In the Program file of a Blazor WebAssembly app:

using Microsoft.AspNetCore.Components.Web;
using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
using BlazorWebAssemblyTransientDisposable;

var builder = WebAssemblyHostBuilder.CreateDefault(args);
builder.DetectIncorrectUsageOfTransients();
builder.RootComponents.Add<App>("#app");
builder.RootComponents.Add<HeadOutlet>("head::after");

builder.Services.AddTransient<TransientDisposable>();
builder.Services.AddScoped(sp => 
    new HttpClient
    { 
        BaseAddress = new Uri(builder.HostEnvironment.BaseAddress)
    });

var host = builder.Build();
host.EnableTransientDisposableDetection();
await host.RunAsync();

The app can register transient disposables without throwing an exception. However, attempting to resolve a transient disposable results in an InvalidOperationException, as the following example shows.

TransientExample.razor:

@page "/transient-example"
@inject TransientDisposable TransientDisposable

<h1>Transient Disposable Detection</h1>

Navigate to the TransientExample component at /transient-example and an InvalidOperationException is thrown when the framework attempts to construct an instance of TransientDisposable:

System.InvalidOperationException: Trying to resolve transient disposable service TransientDisposable in the wrong scope. Use an 'OwningComponentBase<T>' component base class for the service 'T' you are trying to resolve.

Note

Transient service registrations for IHttpClientFactory handlers are recommended. The TransientExample component in this section indicates the following transient disposables client-side that use authentication, which is expected:

• BaseAddressAuthorizationMessageHandler
• AuthorizationMessageHandler

Detect server-side transient disposables

The following example shows how to detect server-side disposable transient services in an app that should use OwningComponentBase. For more information, see the Utility base component classes to manage a DI scope section.

DetectIncorrectUsagesOfTransientDisposables.cs:

using Microsoft.AspNetCore.Components.Server.Circuits;
using Microsoft.Extensions.DependencyInjection.Extensions;

namespace Microsoft.Extensions.DependencyInjection
{
    using BlazorServerTransientDisposable;

    public static class WebHostBuilderTransientDisposableExtensions
    {
        public static WebApplicationBuilder DetectIncorrectUsageOfTransients(
            this WebApplicationBuilder builder)
        {
            builder.Host
                .UseServiceProviderFactory(
                    new DetectIncorrectUsageOfTransientDisposablesServiceFactory())
                .ConfigureServices(
                    s => s.TryAddEnumerable(ServiceDescriptor.Scoped<CircuitHandler,
                        ThrowOnTransientDisposableHandler>()));

            return builder;
        }
    }
}

namespace BlazorServerTransientDisposable
{
    internal class ThrowOnTransientDisposableHandler : CircuitHandler
    {
        public ThrowOnTransientDisposableHandler(
            ThrowOnTransientDisposable throwOnTransientDisposable)
        {
            throwOnTransientDisposable.ShouldThrow = true;
        }
    }

    public class DetectIncorrectUsageOfTransientDisposablesServiceFactory 
        : IServiceProviderFactory<IServiceCollection>
    {
        public IServiceCollection CreateBuilder(IServiceCollection services) => 
            services;

        public IServiceProvider CreateServiceProvider(
            IServiceCollection containerBuilder)
        {
            var collection = new ServiceCollection();

            foreach (var descriptor in containerBuilder)
            {
                if (descriptor.Lifetime == ServiceLifetime.Transient &&
                    descriptor.ImplementationType != null && 
                    typeof(IDisposable).IsAssignableFrom(
                        descriptor.ImplementationType))
                {
                    collection.Add(CreatePatchedDescriptor(descriptor));
                }
                else if (descriptor.Lifetime == ServiceLifetime.Transient &&
                         descriptor.ImplementationFactory != null)
                {
                    collection.Add(CreatePatchedFactoryDescriptor(descriptor));
                }
                else
                {
                    collection.Add(descriptor);
                }
            }

            collection.AddScoped<ThrowOnTransientDisposable>();

            return collection.BuildServiceProvider();
        }

        private ServiceDescriptor CreatePatchedFactoryDescriptor(
            ServiceDescriptor original)
        {
            var newDescriptor = new ServiceDescriptor(
                original.ServiceType,
                (sp) =>
                {
                    var originalFactory = original.ImplementationFactory;

                    if (originalFactory is null)
                    {
                        throw new InvalidOperationException(
                            "originalFactory is null.");
                    }

                    var originalResult = originalFactory(sp);

                    var throwOnTransientDisposable = 
                        sp.GetRequiredService<ThrowOnTransientDisposable>();
                    if (throwOnTransientDisposable.ShouldThrow && 
                        originalResult is IDisposable d)
                    {
                        throw new InvalidOperationException("Trying to resolve " +
                            $"transient disposable service {d.GetType().Name} in " +
                            "the wrong scope. Use an 'OwningComponentBase<T>' " +
                            "component base class for the service 'T' you are " +
                            "trying to resolve.");
                    }

                    return originalResult;
                },
                original.Lifetime);

            return newDescriptor;
        }

        private ServiceDescriptor CreatePatchedDescriptor(
            ServiceDescriptor original)
        {
            var newDescriptor = new ServiceDescriptor(
                original.ServiceType,
                (sp) => {
                    var throwOnTransientDisposable = 
                        sp.GetRequiredService<ThrowOnTransientDisposable>();
                    if (throwOnTransientDisposable.ShouldThrow)
                    {
                        throw new InvalidOperationException("Trying to resolve " +
                            "transient disposable service " +
                            $"{original.ImplementationType?.Name} in the wrong " +
                            "scope. Use an 'OwningComponentBase<T>' component " +
                            "base class for the service 'T' you are trying to " +
                            "resolve.");
                    }

                    if (original.ImplementationType is null)
                    {
                        throw new InvalidOperationException(
                            "ImplementationType is null.");
                    }

                    return ActivatorUtilities.CreateInstance(sp, 
                        original.ImplementationType);
                },
                ServiceLifetime.Transient);
    
            return newDescriptor;
        }
    }

    internal class ThrowOnTransientDisposable
    {
        public bool ShouldThrow { get; set; }
    }
}

TransitiveTransientDisposableDependency.cs:

public class TransitiveTransientDisposableDependency 
    : ITransitiveTransientDisposableDependency, IDisposable
{
    public void Dispose() { }
}

public interface ITransitiveTransientDisposableDependency
{
}

public class TransientDependency
{
    private readonly ITransitiveTransientDisposableDependency 
        transitiveTransientDisposableDependency;

    public TransientDependency(ITransitiveTransientDisposableDependency 
        transitiveTransientDisposableDependency)
    {
        this.transitiveTransientDisposableDependency = 
            transitiveTransientDisposableDependency;
    }
}

The TransientDependency in the following example is detected.

In the Program file:

builder.DetectIncorrectUsageOfTransients();
builder.Services.AddTransient<TransientDependency>();
builder.Services.AddTransient<ITransitiveTransientDisposableDependency, 
    TransitiveTransientDisposableDependency>();

The app can register transient disposables without throwing an exception. However, attempting to resolve a transient disposable results in an InvalidOperationException, as the following example shows.

Components/Pages/TransientExample.razor:

@page "/transient-example"
@inject TransientDependency TransientDependency

<h1>Transient Disposable Detection</h1>

Navigate to the TransientExample component at /transient-example and an InvalidOperationException is thrown when the framework attempts to construct an instance of TransientDependency:

System.InvalidOperationException: Trying to resolve transient disposable service TransientDependency in the wrong scope. Use an 'OwningComponentBase<T>' component base class for the service 'T' you are trying to resolve.

Access server-side Blazor services from a different DI scope

Circuit activity handlers provide an approach for accessing scoped Blazor services from other non-Blazor dependency injection (DI) scopes, such as scopes created using IHttpClientFactory.

Prior to the release of ASP.NET Core 8.0, accessing circuit-scoped services from other dependency injection scopes required using a custom base component type. With circuit activity handlers, a custom base component type isn't required, as the following example demonstrates:

public class CircuitServicesAccessor
{
    static readonly AsyncLocal<IServiceProvider> blazorServices = new();

    public IServiceProvider? Services
    {
        get => blazorServices.Value;
        set => blazorServices.Value = value;
    }
}

public class ServicesAccessorCircuitHandler : CircuitHandler
{
    readonly IServiceProvider services;
    readonly CircuitServicesAccessor circuitServicesAccessor;

    public ServicesAccessorCircuitHandler(IServiceProvider services, 
        CircuitServicesAccessor servicesAccessor)
    {
        this.services = services;
        this.circuitServicesAccessor = servicesAccessor;
    }

    public override Func<CircuitInboundActivityContext, Task> CreateInboundActivityHandler(
        Func<CircuitInboundActivityContext, Task> next)
    {
        return async context =>
        {
            circuitServicesAccessor.Services = services;
            await next(context);
            circuitServicesAccessor.Services = null;
        };
    }
}

public static class CircuitServicesServiceCollectionExtensions
{
    public static IServiceCollection AddCircuitServicesAccessor(
        this IServiceCollection services)
    {
        services.AddScoped<CircuitServicesAccessor>();
        services.AddScoped<CircuitHandler, ServicesAccessorCircuitHandler>();

        return services;
    }
}

Access the circuit-scoped services by injecting the CircuitServicesAccessor where it's needed.

For an example that shows how to access the AuthenticationStateProvider from a DelegatingHandler set up using IHttpClientFactory, see Server-side ASP.NET Core Blazor additional security scenarios.

Additional resources

• Dependency injection in ASP.NET Core
• IDisposable guidance for Transient and shared instances
• Dependency injection into views in ASP.NET Core