Stackoverflow Exception in MediatR Ping Sample?-CodePudding

While invoking the handler I get

info: Microsoft.Hosting.Lifetime[0] Content root path: C:\S\Abhi.MediatR.SampleUsingControllers Stack overflow. Repeat 260 times:

Could you help me with, what did is missing?

To invoke the handler, I had created a controller as below:

[Route("api/[controller]")]
[ApiController]
public class PingController : ControllerBase
{
    private readonly IMediator mediator;

    public PingController(IMediator mediator)
    {
        this.mediator = mediator;
    }

    [HttpGet]
    [Produces(typeof(string))]
    public IActionResult Get()
    {
        try
        {
            var response = mediator.Send(new Ping());
            return Ok(response);
        }
        catch (Exception ex)
        {
            return BadRequest($"Oops something went wrong, {ex}");
        }
    }
}

Created Ping Request

public class Ping : IRequest<string>
{
}

Created PingHandler:

public class PingHandler : IRequestHandler<Ping, string>
{
    private readonly IMediator mediator;

    public PingHandler(IMediator mediator)
    {
        this.mediator = mediator;
    }

    public async Task<string> Handle(Ping request, CancellationToken cancellationToken)
    {
        //return Task.FromResult("Pong");

        var response = await mediator.Send(new Ping());

        return response;
    }
}

In Program.cs have added the MediatR

builder.Services.AddMediatR(typeof(Program));

As per doc I also tried adding as below:

builder.Services.AddMediatR(Assembly.GetExecutingAssembly());

CodePudding user response：

The exception shows that you have an infinite recursion in your code. Handle method is again calling the Ping request again.

you need to uncomment the line return Task.FromResult("Pong");

and comment the below code.

var response = await mediator.Send(new Ping());
return response;