[WebToolsE2E][Aspire]After adding 'Aspire.Npgsql.EntityFrameworkCore.PostgreSQL' component and updating related codes, F5 failed with an exception: 'Some services are not able to be constructed ...'

[v-cazhang]

INSTALL STEPS

1. Clean machine: Win11 x64 23h2 ENU
2. Install VS 17.9 P1 from build [34307.189.d17.9]
3. Apply NuGet Feeds

REPRO STEPS

1. In the VS, create a new project > ASP.NET Core Web App(Razor Page) > .NET 8.0 > check 'Enlist in Aspire Orchestration' > Create
2. Right-click the Models folder > Add > Class, named Movie.cs and paste following codes:

	public class Movie
	{
	    public int ID { get; set; }
	    public string Title { get; set; } = string.Empty;
	    public DateTime ReleaseDate { get; set; }
	    public string Genre { get; set; } = string.Empty;
	    public decimal Price { get; set; }
	}

3. Right-click the Controllers folder > add > Controller > Mvc Controller with views, using Entity Framework:

   • Model class: Movies.cs
   • DbContext class: click '+' to create a new db context
   • Database provider: select PstgreSQL

4. Right-click the razor project > Add > Aspire component > Aspire.Npgsql.EntityFrameworkCore.PostgreSQL using matched version.

5. Open appsettings.json file under Razor project, type following codes:

"Aspire": {
	    "Npgsql": {
	      "EntityFrameworkCore": {
	        "PostgreSQL": {
	          "DbContextPooling": true,
	          "HealthChecks": false,
	          "Tracing": false
	        }
	      }
	    }
	  }

6. Then open Program.cs of razor project, type following codes and replace with the DbContext created in step 3:
   builder.AddNpgsqlDbContext<MyDbContext>("myConnection");
7. Open appsettings.json of xxx.AppHost project, add following codes and replace with the connection string created in step 3:

"ConnectionStrings": {
	        "myConnection": "Host=myserver;Database=test"
	      }

8. Open Program.cs of xxx.AppHost project, add following codes:

var postgresdb = builder.AddPostgresContainer("pg").AddDatabase("postgresdb");

var myService = builder.AddProject<Projects.MyService>()
                       .WithReference(postgresdb);

9. F5

ACTUAL
F5 failed with an exception

System.AggregateException
HResult=0x80131500
Message=Some services are not able to be constructed (Error while validating the service descriptor 'ServiceType: Microsoft.EntityFrameworkCore.Internal.IDbContextPool1[WebApplication4.Data.WebApplication4Context] Lifetime: Singleton ImplementationType: Microsoft.EntityFrameworkCore.Internal.DbContextPool1[WebApplication4.Data.WebApplication4Context]': Cannot consume scoped service 'Microsoft.EntityFrameworkCore.DbContextOptions1[WebApplication4.Data.WebApplication4Context]' from singleton 'Microsoft.EntityFrameworkCore.Internal.IDbContextPool1[WebApplication4.Data.WebApplication4Context]'.) (Error while validating the service descriptor 'ServiceType: Microsoft.EntityFrameworkCore.Internal.IScopedDbContextLease1[WebApplication4.Data.WebApplication4Context] Lifetime: Scoped ImplementationType: Microsoft.EntityFrameworkCore.Internal.ScopedDbContextLease1[WebApplication4.Data.WebApplication4Context]': Cannot consume scoped service 'Microsoft.EntityFrameworkCore.DbContextOptions1[WebApplication4.Data.WebApplication4Context]' from singleton 'Microsoft.EntityFrameworkCore.Internal.IDbContextPool1[WebApplication4.Data.WebApplication4Context]'.)
Source=Microsoft.Extensions.DependencyInjection
StackTrace:
at Microsoft.Extensions.DependencyInjection.ServiceProvider..ctor(ICollection`1 serviceDescriptors, ServiceProviderOptions options)
at Microsoft.Extensions.DependencyInjection.ServiceCollectionContainerBuilderExtensions.BuildServiceProvider(IServiceCollection services, ServiceProviderOptions options)
at Microsoft.Extensions.Hosting.HostApplicationBuilder.Build()
at Microsoft.AspNetCore.Builder.WebApplicationBuilder.Build()
at Program.

$(String[] args) in C:\Users\v-cazhang\source\repos\WebApplication4\WebApplication4\Program.cs:line 14

This exception was originally thrown at this call stack:
[External Code]

Inner Exception 1:
InvalidOperationException: Error while validating the service descriptor 'ServiceType: Microsoft.EntityFrameworkCore.Internal.IDbContextPool1[WebApplication4.Data.WebApplication4Context] Lifetime: Singleton ImplementationType: Microsoft.EntityFrameworkCore.Internal.DbContextPool1[WebApplication4.Data.WebApplication4Context]': Cannot consume scoped service 'Microsoft.EntityFrameworkCore.DbContextOptions1[WebApplication4.Data.WebApplication4Context]' from singleton 'Microsoft.EntityFrameworkCore.Internal.IDbContextPool1[WebApplication4.Data.WebApplication4Context]'.

Inner Exception 2:
InvalidOperationException: Cannot consume scoped service 'Microsoft.EntityFrameworkCore.DbContextOptions1[WebApplication4.Data.WebApplication4Context]' from singleton 'Microsoft.EntityFrameworkCore.Internal.IDbContextPool1[WebApplication4.Data.WebApplication4Context]'.

EXPECTED
Running the solution succeed and can show the dashboard.

[DamianEdwards]

This is due to the scaffolding adding the line to register the DbContext and that line conflicting with the Aspire version builder.AddNpgsqlDbContext. Remove the non-Aspire line and it should work.

We should explore how we can detect this better and provide a clearer exception message.

[v-cazhang]

This issue doesn't repro after removing the line which registered the DbContext.

[eerhardt]

@DamianEdwards - how common do you imagine this scenario would happen? Is this something we should address soon?

[DamianEdwards]

Scaffolding use is pretty high, so I expect this will happen a lot. We could possibly update scaffolding to special-case detecting the Aspire methods, or we could look updating the Aspire methods to do runtime checks to better detect this situation and throw a helpful exception, perhaps only enabled when in development (another kind of DI validity check).

[eerhardt]

Maybe both?
Does scaffolding always add this line if it isn't there? I would be really annoyed if every time I scaffolded it kept adding back in this line that I needed to remove.

[DamianEdwards]

Yeah good point. It obviously doesn't scale to any other method that might be doing it under the covers but it seems like it's fair we should update our scaffolders to understand our top-level methods. Logged dotnet/Scaffolding#2590 to track updating scaffolding.

[eerhardt]

@sebastienros - is this something you can handle in preview5? (since you did the EF API work in preview4). It should be simple enough to just check in the AddXXXDbContext methods (when the app is in "Development") if the DbContext has already been added to the DI container, and throw a useful exception.