在 ASP.NET Web API 中处理 ModelState 验证

Question

我想知道如何使用 ASP.NET Web API 实现模型验证。我的模型是这样的：

public class Enquiry
{
    [Key]
    public int EnquiryId { get; set; }
    [Required]
    public DateTime EnquiryDate { get; set; }
    [Required]
    public string CustomerAccountNumber { get; set; }
    [Required]
    public string ContactName { get; set; }
}

然后我的 API 控制器中有一个 Post 操作：

public void Post(Enquiry enquiry)
{
    enquiry.EnquiryDate = DateTime.Now;
    context.DaybookEnquiries.Add(enquiry);
    context.SaveChanges();
}

如何添加if(ModelState.IsValid)，然后处理错误信息传递给用户？

Answer 1

为了关注点分离，我建议你使用动作过滤器进行模型验证，所以你不需要太关心如何在你的 api 控制器中进行验证：

using System.Net;
using System.Net.Http;
using System.Web.Http.Controllers;
using System.Web.Http.Filters;

namespace System.Web.Http.Filters
{
    public class ValidationActionFilter : ActionFilterAttribute
    {
        public override void OnActionExecuting(HttpActionContext actionContext)
        {
            var modelState = actionContext.ModelState;

            if (!modelState.IsValid)
                actionContext.Response = actionContext.Request
                     .CreateErrorResponse(HttpStatusCode.BadRequest, modelState);
        }
    }
}

Answer 2

也许不是您想要的，但也许有人知道是件好事：

如果您使用的是 .net Web Api 2，您可以执行以下操作：

if (!ModelState.IsValid)
     return BadRequest();

根据模型错误，您会得到以下结果：

{
   Message: "The request is invalid."
   ModelState: {
       model.PropertyA: [
            "The PropertyA field is required."
       ],
       model.PropertyB: [
             "The PropertyB field is required."
       ]
   }
}

Answer 3

像这样，例如：

public HttpResponseMessage Post(Person person)
{
    if (ModelState.IsValid)
    {
        PersonDB.Add(person);
        return Request.CreateResponse(HttpStatusCode.Created, person);
    }
    else
    {
        // the code below should probably be refactored into a GetModelErrors
        // method on your BaseApiController or something like that

        var errors = new List<string>();
        foreach (var state in ModelState)
        {
            foreach (var error in state.Value.Errors)
            {
                errors.Add(error.ErrorMessage);
            }
        }
        return Request.CreateResponse(HttpStatusCode.Forbidden, errors);
    }
}

这将返回这样的响应（假设为 JSON，但 XML 的基本原理相同）：

HTTP/1.1 400 Bad Request
Content-Type: application/json; charset=utf-8
(some headers removed here)

["A value is required.","The field First is required.","Some custom errorm essage."]

您当然可以按照自己喜欢的方式构建错误对象/列表，例如添加字段名称、字段 ID 等。

即使它是一个“单向”Ajax 调用，例如一个新实体的 POST，您仍然应该向调用者返回一些东西——指示请求是否成功的东西。想象一个网站，您的用户将通过 AJAX POST 请求添加一些关于他们自己的信息。如果他们尝试输入的信息无效怎么办 - 他们如何知道他们的保存操作是否成功？

最好的方法是使用Good Old HTTP Status Codes，比如200 OK等等。这样，您的 JavaScript 就可以使用正确的回调（错误、成功等）正确处理故障。

这里有一个关于此方法更高级版本的不错的教程，使用 ActionFilter 和 jQuery：http://asp.net/web-api/videos/getting-started/custom-validation

Answer 4

或者，如果您正在为您的应用寻找简单的错误集合.. 这是我的实现：

public override void OnActionExecuting(HttpActionContext actionContext)
    {
        var modelState = actionContext.ModelState;

        if (!modelState.IsValid) 
        {

            var errors = new List<string>();
            foreach (var state in modelState)
            {
                foreach (var error in state.Value.Errors)
                {
                    errors.Add(error.ErrorMessage);
                }
            }

            var response = new { errors = errors };

            actionContext.Response = actionContext.Request
                .CreateResponse(HttpStatusCode.BadRequest, response, JsonMediaTypeFormatter.DefaultMediaType);
        }
    }

错误消息响应如下所示：

{
  "errors": [
    "Please enter a valid phone number (7+ more digits)",
    "Please enter a valid e-mail address"
  ]
}

Answer 5

您可以使用System.ComponentModel.DataAnnotations 命名空间中的属性来设置验证规则。详情请参考Model Validation - By Mike Wasson。

另请参考视频ASP.NET Web API, Part 5: Custom Validation - Jon Galloway

其他参考资料

1. Take a Walk on the Client Side with WebAPI and WebForms
2. How ASP.NET Web API binds HTTP messages to domain models, and how to work with media formats in Web API.
3. Dominick Baier - Securing ASP.NET Web APIs
4. Hooking AngularJS validation to ASP.NET Web API Validation
5. Displaying ModelState Errors with AngularJS in ASP.NET MVC
6. How to render errors to client? AngularJS/WebApi ModelState
7. Dependency-Injected Validation in Web API

Answer 6

在startup.cs文件中添加以下代码

services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2).ConfigureApiBehaviorOptions(options =>
            {
                options.InvalidModelStateResponseFactory = (context) =>
                {
                    var errors = context.ModelState.Values.SelectMany(x => x.Errors.Select(p => new ErrorModel()
                   {
                       ErrorCode = ((int)HttpStatusCode.BadRequest).ToString(CultureInfo.CurrentCulture),
                        ErrorMessage = p.ErrorMessage,
                        ServerErrorMessage = string.Empty
                    })).ToList();
                    var result = new BaseResponse
                    {
                        Error = errors,
                        ResponseCode = (int)HttpStatusCode.BadRequest,
                        ResponseMessage = ResponseMessageConstants.VALIDATIONFAIL,

                    };
                    return new BadRequestObjectResult(result);
                };
           });

Answer 7

C#

    public class ValidateModelAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(HttpActionContext actionContext)
        {
            if (actionContext.ModelState.IsValid == false)
            {
                actionContext.Response = actionContext.Request.CreateErrorResponse(
                    HttpStatusCode.BadRequest, actionContext.ModelState);
            }
        }
    }

...

    [ValidateModel]
    public HttpResponseMessage Post([FromBody]AnyModel model)
    {

Javascript

$.ajax({
        type: "POST",
        url: "/api/xxxxx",
        async: 'false',
        contentType: "application/json; charset=utf-8",
        data: JSON.stringify(data),
        error: function (xhr, status, err) {
            if (xhr.status == 400) {
                DisplayModelStateErrors(xhr.responseJSON.ModelState);
            }
        },
....


function DisplayModelStateErrors(modelState) {
    var message = "";
    var propStrings = Object.keys(modelState);

    $.each(propStrings, function (i, propString) {
        var propErrors = modelState[propString];
        $.each(propErrors, function (j, propError) {
            message += propError;
        });
        message += "\n";
    });

    alert(message);
};

Answer 8

这里可以勾选以一一显示模型状态错误

 public HttpResponseMessage CertificateUpload(employeeModel emp)
    {
        if (!ModelState.IsValid)
        {
            string errordetails = "";
            var errors = new List<string>();
            foreach (var state in ModelState)
            {
                foreach (var error in state.Value.Errors)
                {
                    string p = error.ErrorMessage;
                    errordetails = errordetails + error.ErrorMessage;

                }
            }
            Dictionary<string, object> dict = new Dictionary<string, object>();



            dict.Add("error", errordetails);
            return Request.CreateResponse(HttpStatusCode.BadRequest, dict);


        }
        else
        {
      //do something
        }
        }

}

Answer 9

我在实现accepted solution pattern 时遇到问题，我的ModelStateFilter 对于某些模型对象的actionContext.ModelState.IsValid 总是返回false（随后返回400）：

public class ModelStateFilter : ActionFilterAttribute
{
    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        if (!actionContext.ModelState.IsValid)
        {
            actionContext.Response = new HttpResponseMessage { StatusCode = HttpStatusCode.BadRequest};
        }
    }
}

我只接受 JSON，所以我实现了一个自定义模型绑定器类：

public class AddressModelBinder : System.Web.Http.ModelBinding.IModelBinder
{
    public bool BindModel(HttpActionContext actionContext, System.Web.Http.ModelBinding.ModelBindingContext bindingContext)
    {
        var posted = actionContext.Request.Content.ReadAsStringAsync().Result;
        AddressDTO address = JsonConvert.DeserializeObject<AddressDTO>(posted);
        if (address != null)
        {
            // moar val here
            bindingContext.Model = address;
            return true;
        }
        return false;
    }
}

我通过

在我的模型之后直接注册

config.BindParameter(typeof(AddressDTO), new AddressModelBinder());

Answer 10

您还可以抛出异常，如下所述： http://blogs.msdn.com/b/youssefm/archive/2012/06/28/error-handling-in-asp-net-webapi.aspx

注意，按照文章的建议，请记住包含 System.Net.Http

Answer 11

把这个放到startup.cs文件中

 services.AddMvc().ConfigureApiBehaviorOptions(options =>
        {
            options.InvalidModelStateResponseFactory = (context) =>
            {
                var errors = context.ModelState.Values.SelectMany(x => x.Errors.Select(p =>p.ErrorMessage)).ToList();                    
                var result = new Response
                {
                    Succeeded = false,
                    ResponseMessage = string.Join(", ",errors)
                };
                return new BadRequestObjectResult(result);
            };
        });