c# - ServiceStack FluentValidation 中的自定义响应 DTO

Question

我正在评估 FluentValidation in ServiceStack用于处理请求 DTO 的自动验证:

Plugins.Add(new ValidationFeature());
container.RegisterValidators(typeof(MyValidator).Assembly);

错误通过序列化 ErrorResponse DTO 返回给客户端，可能如下所示:

{
    "ErrorCode": "GreaterThan",
    "Message": "'Age' must be greater than '0'.",
    "Errors": [
        {
            "ErrorCode": "GreaterThan",
            "FieldName": "Age",
            "Message": "'Age' must be greater than '0'."
        },
        {
            "ErrorCode": "NotEmpty",
            "FieldName": "Company",
            "Message": "'Company' should not be empty."
        }
    ]
}

我想知道是否可以使用不同的响应 DTO 返回错误。例如:

{
    "code": "123",
    "error": "'Age' must be greater than '0'."
}

我知道可以在服务中显式使用验证器:

public MyService : Service
{
    private readonly IValidator<MyRequestDto> validator;
    public MyService(IValidator<MyRequestDto> validator)
    {
        this.validator = validator;
    }

    public object Get(MyRequestDto request)
    {
        var result = this.validator.Validate(request);
        if (!result.IsValid)
        {
            throw new SomeCustomException(result);
        }

        ... at this stage request DTO validation has passed
    }
}

但这里的问题是是否有可能在某处隐式拦截此验证错误，以便我可以替换响应 DTO 并获得更清洁的服务:

public MyService : Service
{
    public object Get(MyRequestDto request)
    {
        ... at this stage request DTO validation has passed
    }
}

---

更新:

在进一步深入研究源代码后，它看起来像是烧到 ValidationFeature 中，更具体地说是它注册的请求过滤器:

public class ValidationFilters
{
    public void RequestFilter(IHttpRequest req, IHttpResponse res, object requestDto)
    {
        var validator = ValidatorCache.GetValidator(req, requestDto.GetType());
        if (validator == null) return;

        var validatorWithHttpRequest = validator as IRequiresHttpRequest;
        if (validatorWithHttpRequest != null)
            validatorWithHttpRequest.HttpRequest = req;

        var ruleSet = req.HttpMethod;
        var validationResult = validator.Validate(
        new ValidationContext(requestDto, null, new MultiRuleSetValidatorSelector(ruleSet)));

        if (validationResult.IsValid) return;

        var errorResponse = DtoUtils.CreateErrorResponse(
            requestDto, validationResult.ToErrorResult());

        res.WriteToResponse(req, errorResponse);
    }
}

通过编写自定义验证功能，我能够达到预期的效果。但也许有更优雅的方式？

Answer 1

我刚刚 checked in a Customization Error hook这允许您指定自定义错误过滤器，以便在下一版本的 ServiceStack (v3.9.44+) 中更轻松地支持此用例。

来自CustomValidationErrorTests您现在可以将 ValidationFeature 配置为使用将返回的自定义错误过滤器，例如:

public override void Configure(Container container)
{
    Plugins.Add(new ValidationFeature { 
        ErrorResponseFilter = CustomValidationError });
    container.RegisterValidators(typeof(MyValidator).Assembly);           
}

public static object CustomValidationError(
    ValidationResult validationResult, object errorDto)
{
    var firstError = validationResult.Errors[0];
    var dto = new MyCustomErrorDto { 
        code = firstError.ErrorCode, error = firstError.ErrorMessage };

    //Ensure HTTP Clients recognize this as an HTTP Error
    return new HttpError(dto, HttpStatusCode.BadRequest, dto.code, dto.error);
}

现在您的 HTTP 客户端将收到您自定义的错误响应:

try
{
    var response = "http://example.org/customerror".GetJsonFromUrl();
}
catch (Exception ex)
{
    ex.GetResponseBody().Print(); 
    //{"code":"GreaterThan","error":"'Age' must be greater than '0'."}
}

警告:以这种方式自定义错误响应时ServiceStack's typed C# clients将不再提供类型化异常，因为他们希望错误响应包含 ResponseStatus DTO 属性。