ASP.NET Core MediatR错误:向容器注册处理程序 [英] ASP.NET Core MediatR error: Register your handlers with the container

问题描述

我有一个.Net Core应用程序，在其中我使用 .AddMediatR 扩展名按照CQRS方法为我的命令和处理程序注册程序集.

I have a .Net Core app where i use the .AddMediatR extension to register the assembly for my commands and handlers following a CQRS approach.

在Startup.cs的ConfigureServices中，我使用了官方包 MediatR.Extensions.Microsoft.DependencyInjection 中的扩展方法，并带有以下参数:

In ConfigureServices in Startup.cs i have used the extension method from the official package MediatR.Extensions.Microsoft.DependencyInjection with the following parameter:

services.AddMediatR(typeof(AddEducationCommand).GetTypeInfo().Assembly);  

命令和命令处理程序类如下:

The command and commandhandler classes are as follow:

AddEducationCommand.cs

public class AddEducationCommand : IRequest<bool>
{
    [DataMember]
    public int UniversityId { get; set; }

    [DataMember]
    public int FacultyId { get; set; }

    [DataMember]
    public string Name { get; set; }
}

AddEducationCommandHandler.cs

public class AddEducationCommandHandler : IRequestHandler<AddEducationCommand, bool>
    {
        private readonly IUniversityRepository _repository;
        public AddEducationCommandHandler(IUniversityRepository repository)
        {
            _repository = repository;
        }

        public async Task<bool> Handle(AddEducationCommand command, CancellationToken cancellationToken)
        {
            var university = await _repository.GetAsync(command.UniversityId);

            university.Faculties
                .FirstOrDefault(f => f.Id == command.FacultyId)
                .CreateEducation(command.Name);

            return await _repository.UnitOfWork.SaveEntitiesAsync();
        }
    }

当我运行执行简单的 await _mediator.Send(command); 代码的REST端点时，我从日志中得到以下错误:

When i run the REST endpoint that executes a simple await _mediator.Send(command); code, i get the following error from my log:

Error constructing handler for request of type MediatR.IRequestHandler`2[UniversityService.Application.Commands.AddEducationCommand,System.Boolean]. Register your handlers withthe container. See the samples in GitHub for examples.

我尝试浏览文档中的官方示例，但没有任何运气.有谁知道我如何配置MediatR使其正常工作?预先感谢.

I tried to look through the official examples from the docs without any luck. Does anyone know how i configure MediatR to work properly? Thanks in advance.

推荐答案

我遇到了同样的问题.

问题是此行代码

services.AddMediatR(typeof(AddEducationCommand).GetTypeInfo().Assembly);

处理所有MediatR IRequest和IRequestHandlers.

handles all the MediatR IRequest and IRequestHandlers.

但是您创建了一个IRepository接口及其实现类，该接口无法由该 MediatR.Extensions.Microsoft.DependencyInjection

but you created an IRepository interface and its implementation class which can't be handled by that MediatR.Extensions.Microsoft.DependencyInjection

因此请保留所有更改，但要添加它-像

so keep all your changes but add this - manually register this like

services.AddScoped(typeof(IUniversityRepository)，typeof(UniversitySqlServerRepository));

然后问题解决了.

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