Raven DB JsonSerializationException无法加载程序集

时间：2013-09-18 17:27:25

标签： c# json.net ravendb

当我尝试检索包含在动态加载的DLL中找到类型的实体列表的文档时，我得到一个JSONSerialisation异常，该异常表明它无法在动态加载的DLL中找到该类型：{ {1}}

我使用RavenDB（build 2681）来存储使用Roslyn创建的实体，尽管我不认为这是一个问题。每个实体都继承一个非动态接口Could not load assembly 'Sandbox_One'。 Raven会话正在.NET MVC 4 Action的任一侧创建（根据Raven example），我能够将动态实体保存到IEntity列表中。

当我尝试从文档中加载实体列表时，出现序列化错误。目前，我只有一个实体类型（Customer）的单个实例（蓝眼睛）。

观察

  • 在数据库中，实体看起来与我期望的完全相同：
{
  "Entities": [
    {
      "$type": "Prometheus.Dynamic.Sandbox_One.Customer, Sandbox_One",
      "Name": "Customer",
      "Eye_colour": "Blue",
      "Age": 9.0,
      "Id": "b0937393-b1bf-4bcb-97d7-1aea7a96e881"
    }
  ]
}

  • 在加载实体时，我会检查已加载程序集的IEntity，AppDomain.CurrentDomain类型的Prometheus.Dynamic.Sandbox_One是否存在。

  • Customer对象引用了动态加载的程序集，我可以像这样反映类型：

    Realm

  • 在RavenDB会话启动后，程序集将加载到MVC操作中。这会有所作为吗？我想象的不是我期望JSON.net序列化程序在var customer = Activator.CreateInstance(realm.Assembly.GetTypes().First());中查找。

代码和例外

异常的完整堆栈跟踪：

[JsonSerializationException: Could not load assembly 'Sandbox_One'.]
   Raven.Imports.Newtonsoft.Json.Serialization.DefaultSerializationBinder.GetTypeFromTypeNameKey(TypeNameKey typeNameKey) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\DefaultSerializationBinder.cs:69
   Raven.Imports.Newtonsoft.Json.Utilities.ThreadSafeStore`2.AddValue(TKey key) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Utilities\ThreadSafeStore.cs:62
   Raven.Imports.Newtonsoft.Json.Serialization.DefaultSerializationBinder.BindToType(String assemblyName, String typeName) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\DefaultSerializationBinder.cs:119
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ReadSpecialProperties(JsonReader reader, Type& objectType, JsonContract& contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue, Object& newValue, String& id) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:473

[JsonSerializationException: Error resolving type specified in JSON 'Prometheus.Dynamic.Sandbox_One.Customer, Sandbox_One'. Path 'Entities[0].$type'.]
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ReadSpecialProperties(JsonReader reader, Type& objectType, JsonContract& contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue, Object& newValue, String& id) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:526
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:344
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:238
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateList(IWrappedCollection wrappedList, JsonReader reader, JsonArrayContract contract, JsonProperty containerProperty, String id) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:1132
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateList(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, Object existingValue, String id) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:572
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:240
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.SetPropertyValue(JsonProperty property, JsonConverter propertyConverter, JsonContainerContract containerContract, JsonProperty containerProperty, JsonReader reader, Object target) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:692
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateObject(Object newObject, JsonReader reader, JsonObjectContract contract, JsonProperty member, String id) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:1593

[JsonSerializationException: Could not read value for property: Entities]
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateObject(Object newObject, JsonReader reader, JsonObjectContract contract, JsonProperty member, String id) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:1602
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:368
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:238
   Raven.Imports.Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\Serialization\JsonSerializerInternalReader.cs:164
   Raven.Imports.Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType) in c:\Builds\RavenDB-Stable\Imports\Newtonsoft.Json\Src\Newtonsoft.Json\JsonSerializer.cs:565
   Raven.Client.Document.InMemoryDocumentSessionOperations.ConvertToEntity(Type entityType, String id, RavenJObject documentFound, RavenJObject metadata) in c:\Builds\RavenDB-Stable\Raven.Client.Lightweight\Document\InMemoryDocumentSessionOperations.cs:457
   Raven.Client.Document.InMemoryDocumentSessionOperations.TrackEntity(Type entityType, String key, RavenJObject document, RavenJObject metadata, Boolean noTracking) in c:\Builds\RavenDB-Stable\Raven.Client.Lightweight\Document\InMemoryDocumentSessionOperations.cs:404
   Raven.Client.Document.InMemoryDocumentSessionOperations.TrackEntity(Type entityType, JsonDocument documentFound) in c:\Builds\RavenDB-Stable\Raven.Client.Lightweight\Document\InMemoryDocumentSessionOperations.cs:388
   Raven.Client.Document.InMemoryDocumentSessionOperations.TrackEntity(JsonDocument documentFound) in c:\Builds\RavenDB-Stable\Raven.Client.Lightweight\Document\InMemoryDocumentSessionOperations.cs:343
   Raven.Client.Document.SessionOperations.LoadOperation.Complete() in c:\Builds\RavenDB-Stable\Raven.Client.Lightweight\Document\SessionOperations\LoadOperation.cs:61
   Raven.Client.Document.DocumentSession.Load(String id) in c:\Builds\RavenDB-Stable\Raven.Client.Lightweight\Document\DocumentSession.cs:230
   Prometheus.Core.DomainServices.DataManager.GetDataForRealm(IDocumentSession session, Realm realm) in c:\TeamProjectsCloud\Prometheus\Prometheus.Core\DomainServices\DataManager.cs:48
   Prometheus.Portal.Controllers.DataController.Index(String entityName) in c:\TeamProjectsCloud\Prometheus\Prometheus.Portal\Controllers\DataController.cs:23
   lambda_method(Closure , ControllerBase , Object[] ) +192
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +274
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +39
   System.Web.Mvc.Async.c__DisplayClass39.b__33() +120
   System.Web.Mvc.Async.c__DisplayClass4f.b__49() +452
   System.Web.Mvc.Async.c__DisplayClass37.b__36(IAsyncResult asyncResult) +15
   System.Web.Mvc.Async.c__DisplayClass2a.b__20() +33
   System.Web.Mvc.Async.c__DisplayClass25.b__22(IAsyncResult asyncResult) +240
   System.Web.Mvc.c__DisplayClass1d.b__18(IAsyncResult asyncResult) +28
   System.Web.Mvc.Async.c__DisplayClass4.b__3(IAsyncResult ar) +15
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +53
   System.Web.Mvc.Async.c__DisplayClass4.b__3(IAsyncResult ar) +15
   System.Web.Mvc.c__DisplayClass8.b__3(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.c__DisplayClass4.b__3(IAsyncResult ar) +15
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +606
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +288

控制器（我已加强实体加载的调用）： NB AppDomain从基本控制器继承，与MVC site example

完全相同 
RavenSession

抛出异常的Load调用：

public ActionResult Index(string entityName)
{
     var viewModel = new DataViewModel();
     var realm = realmManager.GetRealm(RavenSession, viewModel.SelectedRealm);
     viewModel.Entities = realmManager.GetEntities(realm);
     viewModel.CurrentEntity = viewModel.Entities.SingleOrDefault(x => x.Name == entityName);
     viewModel.Data = dataManager.GetDataForRealm(RavenSession, realm); // Call to loading method

     return View(viewModel);
}

Realm Data类：

    public List<IEntity> GetDataForRealm(IDocumentSession session, Realm realm)
    {
        var realmData = session.Load<RealmData>(realm.RealmDataId); // Exception thrown
        return realmData.Entities;
    }

提前感谢您的帮助！

1 个答案:

答案 0 :(得分：2)

我的解决方案是在App Domain上实现AssemblyResolve事件处理程序。

GetDataForRealm方法变为：

public List<IEntity> GetDataForRealm(IDocumentSession session, Realm realm)
    {
        AppDomain.CurrentDomain.AssemblyResolve += (s, a) => MyResolveEventHandler(s, a, realm.Assembly);

        var realmData = session.Load<RealmData>(realm.RealmDataId);
        return realmData.Entities;
    }

事件处理程序如下所示：

private Assembly MyResolveEventHandler(object sender, ResolveEventArgs args, Assembly assembly)
    {
        if (assembly.GetName().Name == args.Name)
        {
            return assembly;
        }
        return null;
    }

我认为发生了什么：

当JSON.Net反序列化器反映出动态类型时，它无法在AppDomain.CurrentDomain中找到程序集。当AppDomain无法按名称查找程序集时，将调用该处理程序。我的程序集在AppDomain中（因为我使用了Assembly.Load）但是找不到它。

注意： 我用额外的参数扩展了MyResolveEventHandler，因为我已经拥有了我需要的程序集。如果您没有内存中的程序集（但知道它在哪里），那么您可以在MyResovleEventHandler内加载它。

更新

您可能会发现以后在向这些结果对象分配数据时遇到问题。这是因为通过AppDomain传递实体并不意味着它会更改对象的域。相反，它只是提供参考。相反，我发现使用在成员中具有动态程序集的自定义JSON转换器，首先让RavenDB更容易在正确的（临时）域中创建对象。 See that solution here

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