Question

我有一个ASP.NET Core API，我尝试在其中将FluentValidation与Mediatr一起使用。

当前，当控制器方法尝试在其生成的mediatr实例上调用Send时：

抛出异常：“ System.InvalidOperationException” Microsoft.Extensions.DependencyInjection.dll：'无法解析尝试激活类型为“ GetApplicationQuery”的服务 “ GetApplicationQueryValidator”。

查询，验证器和响应类如下：

public class GetApplicationQuery : IRequest<Response>
{
    private string _name;
    public GetApplicationQuery(string name)
    {
        _name = name;
    }

    public string Name { get { return _name; } }
}

public class GetApplicationQueryHandler : IRequestHandler<GetApplicationQuery, Response>
{

    public GetApplicationQueryHandler() { }

    public async Task<Response> Handle(GetApplicationQuery request, CancellationToken cancellationToken)
    {
        return new Response("yadda yadda");            
    }
}

public class GetApplicationQueryValidator : AbstractValidator<GetApplicationQuery>
{
    public GetApplicationQueryValidator(GetApplicationQuery request)
    {   
        RuleFor(m => m.Name).MinimumLength(30).WithMessage("Name must be greater than 30 characters, long");
    }
}

public class Response
{
    private readonly IList<string> _messages = new List<string>();

    public IEnumerable<string> Errors { get; }
    public object Result { get; }

    public Response() => Errors = new ReadOnlyCollection<string>(_messages);

    public Response(object result) : this() => Result = result;

    public Response AddError(string message)
    {
        _messages.Add(message);
        return this;
    }
}

我在Startup类中具有的配置如下：

public void ConfigureServices(IServiceCollection services)
{
    AddMediatr(services);
    services.AddMvc().AddFluentValidation(fv => 
        {
            fv.RegisterValidatorsFromAssemblyContaining<Startup>();
            fv.RunDefaultMvcValidationAfterFluentValidationExecutes = false;
        }).SetCompatibilityVersion(CompatibilityVersion.Version_2_2);           
}

private static void AddMediatr(IServiceCollection services)
{
    const string applicationAssemblyName = "ApplicationApi";
    var assembly = AppDomain.CurrentDomain.Load(applicationAssemblyName);

    AssemblyScanner
        .FindValidatorsInAssembly(assembly)
        .ForEach(result => services.AddScoped(result.InterfaceType, result.ValidatorType));

    services.AddScoped(typeof(IPipelineBehavior<,>), typeof(ValidatorHandler<,>));

    services.AddMediatR(assembly);


}

我猜我的配置错误，但是我几次更改配置都没有成功。

任何指导将不胜感激

Answer 1

GetApplicationQueryValidator将GetApplicationQuery作为构造函数依赖项，但是集合不知道它是否能够注入它。

也没有看到在验证器中如何使用它。我建议从构造函数中删除GetApplicationQuery，因为它看起来不是必需的。

public class GetApplicationQueryValidator : AbstractValidator<GetApplicationQuery> {
    public GetApplicationQueryValidator() { 
        RuleFor(m => m.Name).MinimumLength(30).WithMessage("Name must be greater than 30 characters, long");
    }
}

ASP.NET Core API，Mediatr send方法引发无法解析类型服务的异常

1 个答案: