How to access a service added to DI container from inside Asp.Net Core's ConfigureServices method

Question

The code sample below is from Asp.Net Core ConfigureServices method in Startup.cs.

I am first registering a singleton service called AppState. Subsequent to that, I am configuring OpenIdConnect, and inside the OnTokenValidated lambda, I need to access the AppState service that I just registered in the DI container up above.

What is the most elegant way of accessing the AppState service instance?

I would prefer to not call services.BuildServiceProvider() inside the ConfigureServices method if at all possible.

services.AddSingleton<AppState>();

services.Configure<OpenIdConnectOptions>(AzureADB2CDefaults.OpenIdScheme, options =>
{
    options.Events = new OpenIdConnectEvents
    {
        OnTokenValidated = async ctx =>
        {
            //How to get access to instance of AppState, 
            //which was added to DI container up above
            AppState appState = //{get from DI somehow}; 
            appState.DoSomething();
        }
    };
});

EDIT: Using the answer below, I edited the code like so, but I can confirm that the OnTokenValidated event is not firing, as opposed to the code above in my original question, which does fire:

services.AddOptions<OpenIdConnectOptions>(AzureADB2CDefaults.OpenIdScheme)
            .Configure<IServiceScopeFactory>((options, sp) => {
                using (var scope = sp.CreateScope())
                {
                    options.Events = new OpenIdConnectEvents
                    {
                        OnTokenValidated = async ctx =>
                        {
                            var appState = scope.ServiceProvider.GetRequiredService<AppState>();

                            await appState.Dosomething();         
                        }
                    };
                }
            });

@Nkosi Thanks for your answer...Could you please advise what I might be doing wrong. I have edited my question with the new code, and the OnTokenValidated does not fire. — user2202866
– user2202866, Commented Apr 3, 2020 at 2:00

Nkosi · Accepted Answer · 2020-05-01 13:46:17Z

9

Use the TokenValidatedContext to get access to the current request service provider and resolve the service

services
    .Configure<OpenIdConnectOptions>(AzureADB2CDefaults.OpenIdScheme, options => {
        options.Events = new OpenIdConnectEvents {
            OnTokenValidated = async ctx => {
                //Get access to instance of AppState, 
                //which was added to DI container up above
                AppState appState = ctx.HttpContext.RequestServices
                    .GetRequiredService<AppState>();
                await appState.DoSomething();

                //...
            }
        };
    });

edited May 1, 2020 at 13:46

answered Apr 3, 2020 at 2:37

Nkosi

249k38 gold badges472 silver badges506 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

OJB1 Over a year ago

This has helped me get closer to a similar issue, but what I find here is that the OnTokenValidated event seems to only fire if i log into the WebApp from the home page (when using razor) I'm trying to figure out how to get this to fire when the login process is initiated from any protected page or resource.

Tue Skeltved · Accepted Answer · 2020-05-29 15:31:49Z

4

You can access the DI service from the event context:

services.AddSingleton<AppState>();

services.Configure<OpenIdConnectOptions>(AzureADB2CDefaults.OpenIdScheme, options =>
{
    options.Events = new OpenIdConnectEvents
    {
        OnTokenValidated = async ctx =>
        {
            var appState = (AppState)ctx.HttpContext.RequestServices.GetService(typeof(AppState));
            appState.DoSomething();
        }
    };
});

edited May 29, 2020 at 15:31

answered May 29, 2020 at 12:22

Tue Skeltved

3062 silver badges3 bronze badges

Comments

Jeremy Lakeman · Accepted Answer · 2020-04-03 02:54:36Z

0

Calling services.Configure<T>, adds an IConfigureOptions<T> to the service container that calls your action method; https://github.com/aspnet/Options/blob/master/src/Microsoft.Extensions.Options/OptionsServiceCollectionExtensions.cs#L72

You can define your own implementation of IConfigureOptions<T> and inject any service you like.

answered Apr 3, 2020 at 2:54

Jeremy Lakeman

11.6k30 silver badges34 bronze badges

Comments

farzad khan · Accepted Answer · 2024-10-29 06:21:28Z

To elegantly access the AppState service within the OnTokenValidated event handler without using BuildServiceProvider(), you can inject the AppState instance directly into the event handler using a scoped factory.

Instead of creating a new scope within the Configure lambda, simply capture the IServiceProvider as a parameter and resolve the AppState service within the OnTokenValidated event handler. Here’s the revised code:

services.AddSingleton<AppState>();

services.Configure<OpenIdConnectOptions>(AzureADB2CDefaults.OpenIdScheme, options =>
{
    options.Events = new OpenIdConnectEvents
    {
        OnTokenValidated = async ctx =>
        {
            var appState = ctx.HttpContext.RequestServices.GetRequiredService<AppState>();
            await appState.DoSomething();
        }
    };
});

Over here ctx.HttpContext.RequestServices provides access to the dependency injection container for the current request.

You retrieve the AppState instance from the container without creating an extra service provider or scope.
This method is efficient, as it directly accesses the already registered singleton AppState service within the request's DI context.

This keeps the ConfigureServices method clean and avoids manually managing scopes.

Collectives™ on Stack Overflow

How to access a service added to DI container from inside Asp.Net Core's ConfigureServices method

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related