在MediatR管道上使用多个FluentValidators

// 定义命令对象
public class CreateOrderCommand : IRequest
{
    public string CustomerName { get; set; }
    public string Email { get; set; }
    public decimal TotalAmount { get; set; }
}

// 定义FluentValidators
public class CreateOrderCommandValidator : AbstractValidator<CreateOrderCommand>
{
    public CreateOrderCommandValidator()
    {
        RuleFor(command => command.CustomerName).NotEmpty();
        RuleFor(command => command.Email).NotEmpty().EmailAddress();
        RuleFor(command => command.TotalAmount).GreaterThan(0);
    }
}

public class EmailValidator : AbstractValidator<CreateOrderCommand>
{
    public EmailValidator()
    {
        RuleFor(command => command.Email).Must(BeUniqueEmail).WithMessage("Email已存在");
    }

    private bool BeUniqueEmail(string email)
    {
        // 检查Email是否唯一的逻辑
        // 返回true表示唯一，返回false表示不唯一
    }
}

// 注册FluentValidators
public void ConfigureServices(IServiceCollection services)
{
    services.AddMediatR(typeof(Startup));
    services.AddTransient<IValidator<CreateOrderCommand>, CreateOrderCommandValidator>();
    services.AddTransient<IValidator<CreateOrderCommand>, EmailValidator>();
}

// 执行验证逻辑
public class CreateOrderCommandHandler : IRequestHandler<CreateOrderCommand>
{
    private readonly IValidator<CreateOrderCommand>[] _validators;

    public CreateOrderCommandHandler(IValidator<CreateOrderCommand>[] validators)
    {
        _validators = validators;
    }

    public async Task<Unit> Handle(CreateOrderCommand request, CancellationToken cancellationToken)
    {
        var context = new ValidationContext<CreateOrderCommand>(request);
        var validationResults = await Task.WhenAll(_validators.Select(v => v.ValidateAsync(context, cancellationToken)));
        var failures = validationResults.SelectMany(r => r.Errors).Where(f => f != null).ToList();

        if (failures.Count != 0)
        {
            throw new ValidationException(failures);
        }

        // 处理命令逻辑

        return Unit.Value;
    }
}