How Can I Manually Resolve Services within ASP.NET Core's `ConfigureServices` Method?

Manually resolve the service in the ConfigureServices method of ASP.NET Core

ASP.NET Core uses the IServiceCollection interface to build a dependency injection (DI) container. Once built, it is composed into a IServiceProvider instance that allows you to resolve services. This article guides how to manually parse instances in the ConfigureServices method.

Inject dependencies

The

ConfigureServices method does not allow service injection, so you can inject services into the constructor of the Startup class, such as IConfiguration, IWebHostEnvironment and ILoggerFactory.

public Startup(IConfiguration configuration) => Configuration = configuration;

public void ConfigureServices(IServiceCollection services) => services.AddScoped<IFooService>();

Manually resolve dependencies in Configure()

You can manually resolve the service in the IApplicationBuilder method using the ApplicationServices attribute of Configure():

public void Configure(IApplicationBuilder app)
{
    var serviceProvider = app.ApplicationServices;
    var fooService = serviceProvider.GetService<IFooService>();
}

Manually resolve dependencies in ConfigureServices()

To resolve services in ConfigureServices, use BuildServiceProvider() to construct an intermediate IServiceProvider to access services registered up to that point:

public void ConfigureServices(IServiceCollection services)
{
    services.AddSingleton<IFooService>();
    var sp = services.BuildServiceProvider();
    var fooService = sp.GetService<IFooService>();
}

Warning:

Avoid resolving services in ConfigureServices as it should focus on configuring application services. Consider manually binding the value from IConfiguration to the instance, or using overloads of AddSingleton/AddScoped/AddTransient to lazily create the instance.

Manually resolving services (service locators) is an anti-pattern and should be used with caution.

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