Asp.net DbGeography实体框架的反序列化

我有一个类

事件

，其属性类型为

DbGeography

public class Event
{
    public long Id { get; set; }
    public DateTime Date { get; set; }
    public DbGeography Location { get; set; }
}

在类

DatabaseHelper

中，我尝试从服务器加载数据

public async Task<IEnumerable<Event>> GetEventsAsync()
{
    var uri = new Uri(string.Format(Constants.EventsUrl, string.Empty));
    var content = await _client.GetStringAsync(uri);
    IEnumerable<Event> events = JsonConvert.DeserializeObject<List<Event>>(content);

    return events;
}

我发现我应该使用一个定制的

JsonConverter

// DbGeographyConverter.cs

public class DbGeographyConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return objectType.IsAssignableFrom(typeof(string));
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        JObject location = JObject.Load(reader);
        JToken token = location["Geography"]["WellKnownText"];
        string value = token.ToString();

        System.Data.Entity.Spatial.DbGeography converted = System.Data.Entity.Spatial.DbGeography.PointFromText(value, 4326);
        return converted;
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        // Base serialization is fine 
        serializer.Serialize(writer, value);
    }
}

但在调用返回事件对象列表的函数时，会引发以下错误：

Newtonsoft.Json.JsonSerializationException: Error getting value from 'WellKnownValue' on 'System.Data.Entity.Spatial.DbGeography'.

{"Message":"An error has occurred.","ExceptionMessage":"The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'.","ExceptionType":"System.InvalidOperationException","StackTrace":null,"InnerException":{"Message":"An error has occurred.","ExceptionMessage":"Error while copying content to a stream.","ExceptionType":"System.Net.Http.HttpRequestException","StackTrace":"   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.WebHost.HttpControllerHandler.<WriteBufferedResponseContentAsync>d__1b.MoveNext()","InnerException":{"Message":"An error has occurred.","ExceptionMessage":"Could not load file or assembly 'Newtonsoft.Json, Version=10.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)","ExceptionType":"System.IO.FileLoadException","StackTrace":"   at System.ModuleHandle.ResolveType(RuntimeModule module, Int32 typeToken, IntPtr* typeInstArgs, Int32 typeInstCount, IntPtr* methodInstArgs, Int32 methodInstCount, ObjectHandleOnStack type)
   at System.ModuleHandle.ResolveTypeHandleInternal(RuntimeModule module, Int32 typeToken, RuntimeTypeHandle[] typeInstantiationContext, RuntimeTypeHandle[] methodInstantiationContext)
   at System.Reflection.RuntimeModule.ResolveType(Int32 metadataToken, Type[] genericTypeArguments, Type[] genericMethodArguments)
   at System.Reflection.CustomAttribute.FilterCustomAttributeRecord(CustomAttributeRecord caRecord, MetadataImport scope, Assembly& lastAptcaOkAssembly, RuntimeModule decoratedModule, MetadataToken decoratedToken, RuntimeType attributeFilterType, Boolean mustBeInheritable, Object[] attributes, IList derivedAttributes, RuntimeType& attributeType, IRuntimeMethodInfo& ctor, Boolean& ctorHasParameters, Boolean& isVarArg)
   at System.Reflection.CustomAttribute.IsCustomAttributeDefined(RuntimeModule decoratedModule, Int32 decoratedMetadataToken, RuntimeType attributeFilterType, Int32 attributeCtorToken, Boolean mustBeInheritable)
   at System.Reflection.CustomAttribute.IsDefined(RuntimePropertyInfo property, RuntimeType caType)
   at System.Reflection.RuntimePropertyInfo.IsDefined(Type attributeType, Boolean inherit)
   at Newtonsoft.Json.Serialization.DefaultContractResolver.GetSerializableMembers(Type objectType)
   at Newtonsoft.Json.Serialization.DefaultContractResolver.CreateProperties(Type type, MemberSerialization memberSerialization)
   at Newtonsoft.Json.Serialization.DefaultContractResolver.CreateObjectContract(Type objectType)
   at Newtonsoft.Json.Serialization.DefaultContractResolver.CreateContract(Type objectType)
   at Newtonsoft.Json.Serialization.DefaultContractResolver.ResolveContract(Type type)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.WriteStartArray(JsonWriter writer, Object values, JsonArrayContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IEnumerable values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value, Type objectType)
   at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value, Type objectType)
   at System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, Encoding effectiveEncoding)
   at System.Net.Http.Formatting.JsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, Encoding effectiveEncoding)
   at System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content)
   at System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext, CancellationToken cancellationToken)"}}}

{“Message”：“发生了错误”，“ExceptionMessage”：“ObjectContent`1”类型未能序列化内容类型“application/json；charset=utf-8”的响应正文”，“ExceptionType”：“System.invalidoctionexception”，“StackTrace”：null，“InnerException”：{“Message”：“发生了错误”，“ExceptionMessage”：”：“将内容复制到流时出错。”，“ExceptionType”：“System.Net.Http.HttpRequestException”，“StackTrace”：“在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）时”
在System.Runtime.CompilerServices.TaskWaiter.HandleNonSuccessAndDebuggerNotification（任务任务）中
在System.Web.Http.WebHost.HttpControllerHandler.d_u1b.MoveNext（）“，“InnerException:{”消息“：“发生错误。”，“ExceptionMessage:”无法加载文件或程序集“Newtonsoft.Json，Version=10.0.0，Culture=neutral，PublicKeyToken=30ad4fe6b2a6eed”或其依赖项之一。找到的程序集的清单定义与程序集引用不匹配。（HRESULT中的异常：0x8013100）”，“异常类型”：“System.IO.FileLoadException”，“StackTrace”：在System.ModuleHandle.ResolveType（运行时模块模块、Int32 typeToken、IntPtr*typeInstArgs、Int32 typeInstCount、IntPtr*methodInstArgs、Int32 methodInstCount、ObjectHandleOnStack类型）
位于System.ModuleHandle.ResolveTypeHandleInternal（RuntimeModule模块、Int32 typeToken、RuntimeTypeHandle[]TypeInstanceContext、RuntimeTypeHandle[]MethodInstanceContext）
位于System.Reflection.RuntimeModule.ResolveType（Int32 metadataToken，类型[]genericTypeArguments，类型[]genericMethodArguments）
在System.Reflection.CustomAttribute.FilterCustomAttributeRecord（CustomAttributeRecord caRecord，MetadataImport作用域，Assembly&LastAptCookAssembly，RuntimeModule decoratedModule，MetadataToken decoratedToken，RuntimeType attributeFilterType，Boolean必须不可编辑，Object[]属性、IList-derivedAttributes、RuntimeType和attributeType、IRontimeMethodInfo和ctor、Boolean和ctorHasParameters、Boolean和isVarArg）
在System.Reflection.CustomAttribute.IsCustomAttributeDefined（RuntimeModule decoratedModule、Int32 decoratedMetadataToken、RuntimeType attributeFilterType、Int32 attributeCtorToken、Boolean必须不可编辑）
在System.Reflection.CustomAttribute.IsDefined处（RuntimePropertyInfo属性，RuntimeType caType）
在System.Reflection.RuntimePropertyInfo.IsDefined处（类型attributeType，布尔继承）
位于Newtonsoft.Json.Serialization.DefaultContractResolver.GetSerializableMembers（类型objectType）
位于Newtonsoft.Json.Serialization.DefaultContractResolver.CreateProperties（类型，MemberSerialization MemberSerialization）
位于Newtonsoft.Json.Serialization.DefaultContractResolver.CreateObjectContract（类型objectType）
位于Newtonsoft.Json.Serialization.DefaultContractResolver.CreateContract（类型objectType）
位于Newtonsoft.Json.Serialization.DefaultContractResolver.ResolveContract（类型）
位于Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.WriteStarray（JsonWriter编写器、对象值、JsonArrayContract契约、JsonProperty成员、JsonContainerContract容器契约、JsonProperty容器属性）
位于Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializationList（JsonWriter编写器、IEnumerable值、JsonArrayContract契约、JsonProperty成员、JsonContainerContract集合契约、JsonProperty容器属性）
位于Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializationValue（JsonWriter编写器、对象值、JsonContract valueContract、JsonProperty成员、JsonContainerContract containerContract、JsonProperty containerProperty）
位于Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.serializate（JsonWriter JsonWriter，对象值，类型objectType）
位于Newtonsoft.Json.JsonSerializer.SerializeInternal（JsonWriter JsonWriter，对象值，类型objectType）
位于System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream（类型类型、对象值、流writeStream、编码有效编码）
位于System.Net.Http.Formatting.JsonMediaTypeFormatter.WriteToStream（类型类型、对象值、流writeStream、编码有效编码）
位于System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream（类型类型、对象值、流writeStream、HttpContent）
在System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStreamAsync（类型类型、对象值、流writeStream、HttpContent内容、TransportContext TransportContext、CancellationToken CancellationToken）“}}

---

可能是什么问题？

问题是您引用的是

Newtonsoft.Json 10.0.0.0

Could not load file or assembly 'Newtonsoft.Json, Version=10.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference.

NuGet服务器上似乎不再提供版本

10.0.0.0

，因此您无法在本地使用该版本。无法从何处下载。请尝试更新/安装现有版本。该版本可能会正常工作

Install-Package Newtonsoft.Json -Version 10.0.3