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。我的模型如此：

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)然后处理错误消息以传递给用户？

Answer 1

为了分离关注点，我建议您使用动作过滤器进行模型验证，因此您不需要太在意如何在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

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。

即使它是一种“单向”Ajax调用，就像新实体的POST一样，你仍然应该向调用者返回一些内容 - 这表明请求是否成功。想象一下，您的用户将通过AJAX POST请求添加一些自己的信息。如果他们试图输入的信息无效，他们将如何知道他们的保存行动是否成功该怎么办？

执行此操作的最佳方法是使用 Good Old HTTP Status Codes ，例如200 OK，依此类推。这样，您的JavaScript可以使用正确的回调（错误，成功等）正确处理失败。

这是一个关于此方法的更高级版本的精彩教程，使用ActionFilter和jQuery：http://asp.net/web-api/videos/getting-started/custom-validation

Answer 3

也许不是你想要的东西，但也许有人知道：

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(ModelState);

根据型号错误，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 4

您可以使用System.ComponentModel.DataAnnotations命名空间中的属性来设置验证规则。有关详细信息，请参阅Model Validation - By Mike Wasson。

另请参阅视频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 5

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);
        }
    }

错误消息响应将如下所示：

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

Answer 6

在这里，您可以检查以逐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 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)
    {

的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

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 9

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

注意，要执行该文章建议的内容，请记住包含System.Net.Http

Answer 10

我在实施accepted solution pattern时出现问题，ModelStateFilter对于某些模型对象，false将始终返回actionContext.ModelState.IsValid（以及随后为400）{/ 1}}：

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

直接注册我的模型

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