有什么方法可以将错误代码添加到 ModelState 错误

Question

我正在寻找一种将错误代码与错误消息一起添加到ModelState的方法。 例如

ModelState.AddModelError("ErrorKey", new { Code = 4001, Message = "Some error message" });

对于一些错误的请求，客户端应该执行操作，比较错误消息不是做出决定的理想解决方案。 ModelState.AddModelError方法只接受两个参数，一个错误键和一个消息。 有没有办法实现这个或类似的东西？

Answer 1

不，当您尝试执行以下操作时，没有办法在您的代码中实现您正在寻找的东西：

return BadRequest(ModelState); 

您将收到400 bad request响应，其中包含您已添加的消息（如您​​所见，错误代码已在此处显示）。 因此，在您的情况下，既没有用法也没有添加错误代码的方法。

Answer 2

我找到了一种将错误代码添加到ValidationProblemDetails的方法：

public class CustomValidationProblemDetails : ValidationProblemDetails
{
    public CustomValidationProblemDetails()
    {
    }

    [JsonPropertyName("errors")]
    public new IEnumerable<ValidationError> Errors { get; } = new List<ValidationError>();
}

ValidationProblemDetails有一个Error属性，它是IDictionary<string, string[]>并将这个属性替换为我们的版本以添加代码错误。

public class ValidationError
{
    public int Code { get; set; }

    public string Message { get; set; }
}

ValidationProblemDetails的构造函数接受 ModelStateDictionary 并需要将其转换为ValidationError列表：

public CustomValidationProblemDetails(IEnumerable<ValidationError> errors)
{
    Errors = errors;
}

public CustomValidationProblemDetails(ModelStateDictionary modelState)
{
    Errors = ConvertModelStateErrorsToValidationErrors(modelState);
}

private List<ValidationError> ConvertModelStateErrorsToValidationErrors(ModelStateDictionary modelStateDictionary)
{
    List<ValidationError> validationErrors = new();

    foreach (var keyModelStatePair in modelStateDictionary)
    {
        var errors = keyModelStatePair.Value.Errors;
        switch (errors.Count)
        {
            case 0:
                continue;

            case 1:
                validationErrors.Add(new ValidationError { Code = 100, Message = errors[0].ErrorMessage });
                break;

            default:
                var errorMessage = string.Join(Environment.NewLine, errors.Select(e => e.ErrorMessage));
                validationErrors.Add(new ValidationError { Message = errorMessage });
                break;
        }
    }

    return validationErrors;
}

当我们想要返回错误的请求响应时，创建自定义 ProblemDetailsFactory 以创建 CustomValidationProblemDetails：

public class CustomProblemDetailsFactory : ProblemDetailsFactory
{
    public override ProblemDetails CreateProblemDetails(HttpContext httpContext, int? statusCode = null, string title = null,
        string type = null, string detail = null, string instance = null)
    {
        var problemDetails = new ProblemDetails
        {
            Status = statusCode,
            Title = title,
            Type = type,
            Detail = detail,
            Instance = instance,
        };

        return problemDetails;
    }

    public override ValidationProblemDetails CreateValidationProblemDetails(HttpContext httpContext,
        ModelStateDictionary modelStateDictionary, int? statusCode = null, string title = null, string type = null,
        string detail = null, string instance = null)
    {
        statusCode ??= 400;
        type ??= "https://tools.ietf.org/html/rfc7231#section-6.5.1";
        instance ??= httpContext.Request.Path;

        var problemDetails = new CustomValidationProblemDetails(modelStateDictionary)
        {
            Status = statusCode,
            Type = type,
            Instance = instance
        };

        if (title != null)
        {
            // For validation problem details, don't overwrite the default title with null.
            problemDetails.Title = title;
        }

        var traceId = Activity.Current?.Id ?? httpContext?.TraceIdentifier;
        if (traceId != null)
        {
            problemDetails.Extensions["traceId"] = traceId;
        }

        return problemDetails;
    }
}

最后注册工厂：

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers();

    services.AddTransient<ProblemDetailsFactory, CustomProblemDetailsFactory>();
}

阅读扩展问题详细信息 - 将错误代码添加到 ValidationProblemDetails以获取更多详细信息。