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More examples of Singleton, Transient and Scoped Injection Dependency about docs HOT 3 OPEN

zabpetrus commented on June 25, 2024

More examples of Singleton, Transient and Scoped Injection Dependency

from docs.

Comments (3)

IEvangelist commented on June 25, 2024

Show me what you're trying to do? If you could provide the code that you have, I might be able to help.

from docs.

zabpetrus commented on June 25, 2024

Hello again! I am facing a runtime issue when trying to instantiate an implementation for the 'API.Application.Interfaces.IContatoAppService' interface. The specific error is as follows: System.ArgumentException: 'Cannot instantiate implementation type 'API.Application.Interfaces.IContatoAppService' for service type 'API.Application.Interfaces.IContatoAppService'.' In the Builder I called: builder.Services.AddScoped<IContatoAppService, IContatoAppService>() and I tried other ways too: they all threw an exception. I'm finding it difficult to solve this problem, as it's not clear where exactly the error is (Sorry for the inconvenience, but I've got a project in progress, and from what I know, dependency injection works with Scoped, Singleton and others - but there is another way, which I couldn't identify, but which generates the error ) It would be nice if you could provide more detailed error messages or suggestions about what could be causing this problem, as the error is pointed out in the builder (very generic). Thank you in advance for your assistance! Em qua., 29 de mai. de 2024 às 16:24, David Pine ***@***.***> escreveu:

…

Show me what you're trying to do? If you could provide the code that you have, I might be able to help. — Reply to this email directly, view it on GitHub <#41082 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AQ7OS2J6SBPMZV2FREP2MCLZEYTP7AVCNFSM6AAAAABIKCHCPCVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDCMZYGEYTANBRG4> . You are receiving this because you authored the thread.Message ID: ***@***.***>

from docs.

IEvangelist commented on June 25, 2024

Got it, thank you for the added context, that's very helpful! Ok, I see the issue. When you call:

builder.Services.AddScoped<IContatoAppService, IContatoAppService>();

That's registering a scoped IContatoAppService type with a corresponding implementation of the interface. That's not going to work, since it cannot instantiate an interface, nothing can. Instead, you need to register (or map) the corresponding implementation.

Consider this:

builder.Services.AddScoped<IContatoAppService, DefaultContatoAppService>();

In this example, the implemenation is the DefaultContatoAppService. It has to be defined somewhere:

public class DefaultContatoAppService : IContatoAppService
{
    // TODO: Implement members.
}

Does that make more sense now? Then for unit tests, you could mock the interface and use that.

from docs.

More examples of Singleton, Transient and Scoped Injection Dependency about docs HOT 3 OPEN

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