asp.net-web-api - XML 在 WebApi 中不适用于我 - 与我的数据契约有关

Question

我正在制作一个 Web api 项目，我注意到当我尝试使用 xml 时，我的方法之一失败了。我通常在测试时只使用 json，因为这是我的首选方法，而且效果很好。

public HttpResponseMessage GetStoreNames(StoreDm vm)
        {
            if (ModelState.IsValid)
            {

                var result = storeService.AutoCompleteStore(vm.Latitude, vm.Longitude, vm.Name);
                return Request.CreateResponse <ResponseResult<AutoCompleteSearchDto>>(result.Status.Code, result);

            }


            var responseResult = new ResponseResultWrapper();
            responseResult.Status.Code = HttpStatusCode.BadRequest;
            responseResult.Status.Message = GenericErrors.InvalidRequest;
            responseResult.ModelStateToResponseResult(ModelState);

            return Request.CreateResponse<ResponseResult>(responseResult.Status.Code, responseResult);


        }

 [DataContract(Name = "MyRoot")]
    public class ResponseResultWrapper : ResponseResult
    {
        public void ModelStateToResponseResult(ModelStateDictionary modelState)
        {
            foreach (var kvp in modelState)
            {
                foreach (var error in kvp.Value.Errors)
                {
                    string key = kvp.Key;
                    string msg = error.ErrorMessage;
                    if (String.IsNullOrEmpty(msg))
                    {
                        msg = error.Exception.Message;
                    }

                    base.AddError(key, msg);
                }
            }
        }
    }


 [DataContract(Name = "MyRoot")]
    public class ResponseResult
    {

        public ResponseResult()
        {
            Errors = new Dictionary<string, string>();
            Status = new ResponseBase();
        }

        public void AddError(string key, string errorMessage)
        {
            if (!Errors.ContainsKey(key))
            {
                Errors.Add(key, errorMessage);
            }
        }

        public bool IsValid()
        {
            if (Errors.Count > 0)
            {
                return false;
            }

            return true;
        }

        [DataMember]
        public Dictionary<string, string> Errors { get; private set; }

        [DataMember]
        public ResponseBase Status { get; set; }
    }


    [DataContract(Name = "MyRoot")]
    public class ResponseResult<T> : ResponseResult
    {
        [DataMember]
        public T Response { get; set; }
    }

我收到此错误

HTTP/1.1 500 Internal Server Error
Cache-Control: private
Content-Type: application/xml; charset=utf-8
Server: Microsoft-IIS/8.0
X-AspNet-Version: 4.0.30319
X-SourceFiles: =?UTF-8?B?QzpcVXNlcnNcV2luZG93czdcRGVza3RvcFxQcmljZUNoZWNrXHRydW5rXFByaWNlQ2hlY2tcUHJpY2VDaGVjay5BcGlcYXBpXHN0b3JlXEdldFN0b3JlTmFtZXM=?=
X-Powered-By: ASP.NET
Date: Thu, 23 May 2013 16:44:14 GMT
Content-Length: 2195

<Error><Message>An error has occurred.</Message><ExceptionMessage>The 'ObjectContent`1' type failed to serialize the response body for content type 'application/xml; charset=utf-8'.</ExceptionMessage><ExceptionType>System.InvalidOperationException</ExceptionType><StackTrace /><InnerException><Message>An error has occurred.</Message><ExceptionMessage>Type 'ResponseResultWrapper' with data contract name 'http://schemas.datacontract.org/2004/07/Api.Models' is not expected. Consider using a DataContractResolver or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.</ExceptionMessage><ExceptionType>System.Runtime.Serialization.SerializationException</ExceptionType><StackTrace>   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeAndVerifyType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, Boolean verifyKnownType, RuntimeTypeHandle declaredTypeHandle, Type declaredType)
   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithXsiTypeAtTopLevel(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle originalDeclaredTypeHandle, Type graphType)
   at System.Runtime.Serialization.DataContractSerializer.InternalWriteObjectContent(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver)
   at System.Runtime.Serialization.DataContractSerializer.InternalWriteObject(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver)
   at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver)
   at System.Runtime.Serialization.DataContractSerializer.WriteObject(XmlWriter writer, Object graph)
   at System.Net.Http.Formatting.XmlMediaTypeFormatter.&lt;&gt;c__DisplayClass7.&lt;WriteToStreamAsync&gt;b__6()
   at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action, CancellationToken token)</StackTrace></InnerException></Error>

编辑

[DataContract]
    public class StoreDm
    {
        [DataMember(IsRequired = true)]
        [MinLength(3)]
        public string Name { get; set; }

        [DataMember(IsRequired = true)]
        public double Latitude { get; set; }

        [DataMember(IsRequired = true)]
        public double Longitude { get; set; }
    }

在尝试“Youssef Moussaoui”他的答案的第一部分后，我收到此错误。

There was an error deserializing the object of type StoreDm. The data at the root level is invalid. Line 1, position 1.

我真的无法完成他的第二部分，因为“ResponseResultWrapper”和“ResponeResult”位于两个不同的库中。

Answer 1

尝试改变:

return Request.CreateResponse<ResponseResult>(responseResult.Status.Code, responseResult);

至

return Request.CreateResponse<ResponseResultWrapper>(responseResult.Status.Code, responseResult);

问题在于 DataContractSerializer 需要已知类型来支持继承。您可以在这里了解更多信息:

http://blogs.msdn.com/b/youssefm/archive/2009/04/21/understanding-known-types.aspx

更改 CreateResponse 上的通用参数是最简单的解决方案，但如果您想要序列化 ​​ResponseResult 的派生实例，则需要向 ResponseResult 添加已知类型属性，如下所示:

[DataContract(Name = "MyRoot")]
[KnownType(typeof(ResponseResultWrapper))]
public class ResponseResult
{
}

.