C#•9mo ago

❔ Weird issue with MediaR pipeline.

I have such a typical pipeline UnhandledExceptionBehaviour, which executes before executing command. And it's works fine, for example for this kind of request:

    [HttpPost("addnewguest")]
    public async Task<ActionResult<string>> AddNewGuest(CreateGuestCommand command)
    {
        return await Mediator.Send(command);
    }

    [HttpPost("addnewguest")]
    public async Task<ActionResult<string>> AddNewGuest(CreateGuestCommand command)
    {
        return await Mediator.Send(command);
    }

But when there is no content, this pipeline is omitted. For example:

   [HttpPost("mergeguests")]
    public async Task<ActionResult> MergeGuests(MergeGuestsCommand command)
    {
        await Mediator.Send(command);

        return NoContent();
    }

   [HttpPost("mergeguests")]
    public async Task<ActionResult> MergeGuests(MergeGuestsCommand command)
    {
        await Mediator.Send(command);

        return NoContent();
    }

It is the request:

public record MergeGuestsCommand : IRequest

public record MergeGuestsCommand : IRequest

There used to be a

public record MergeGuestsCommand : IRequest<Unit>

public record MergeGuestsCommand : IRequest<Unit>

, but I read to remove <Unit> in the new version of MediaR and it caused the code to no longer work as it used to. Why?

2 Replies

TYoemtais.z•9mo ago

Ok, found the issue. In new version, there is need to change:

public class UnhandledExceptionBehaviour<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse> where TRequest : IRequest<TResponse>

public class UnhandledExceptionBehaviour<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse> where TRequest : IRequest<TResponse>

To:

public class UnhandledExceptionBehaviour<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse> where TRequest : IBaseRequest

public class UnhandledExceptionBehaviour<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse> where TRequest : IBaseRequest

Accord•9mo ago

Looks like nothing has happened here. I will mark this as stale and this post will be archived until there is new activity.

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❔ Weird issue with MediaR pipeline.