Question

我对编程很不熟悉（在课堂环境之外）。

我正在开发一个有插件的应用程序。每个插件打包/解包它的状态（作为字典）并发送自己以添加到包含所有打包状态的字典中。我正在使用Json.Net来序列化/反序列化并将每个插件传递给它自己的类来打包/解压缩，具体取决于项目是否被保存或打开。

我遇到的问题是当我的第一个插件获取其打包状态的字典版本以解压缩时，我开始重新填充每个属性，第一个属性（字典中的第一个项目）是DataTable。我收到一个错误说：

Unable to cast object of type 'Newtonsoft.Json.Linq.JArray' to 
type 'System.Data.DataTable'.

这是我的序列化代码。

IDictionary<string, IDictionary<string, object>> pluginStates = 
             new Dictionary<string, IDictionary<string, object>>();
signaller.RaiseSaveRequest(pluginStates); //gets all of the plugins' packedState

JsonSerializer serializer = new JsonSerializer();
serializer.ObjectCreationHandling = ObjectCreationHandling.Replace; 
serializer.TypeNameHandling = TypeNameHandling.All; 

using (StreamWriter sw = new StreamWriter(strPathName))
using (JsonWriter writer = new JsonTextWriter(sw))
{
    serializer.Serialize(writer, pluginStates);
}

和反序列化。

 IDictionary<string, IDictionary<string, object>> pluginStates = 
           new Dictionary<string, IDictionary<string, object>>();

 JsonSerializer serializer = new JsonSerializer();
 serializer.ObjectCreationHandling = ObjectCreationHandling.Replace; 
 serializer.TypeNameHandling = TypeNameHandling.All; 

 StreamReader sr = new StreamReader(fullName);
 JsonTextReader reader = new JsonTextReader(sr);
 string json = sr.ReadToEnd();
 pluginStates = serializer.Deserialize<IDictionary<string, IDictionary<string, Object>>>(reader);
 pluginStates = JsonConvert.DeserializeObject<IDictionary<string, IDictionary<string, Object>>>(json);
 sr.Close();
 reader.Close();

 signaller.UnpackProjectState(pluginStates);

我已经尝试过查看NewtonSoft.Json上的文档，但我几乎不了解它以及如何使它在我的代码中运行。一旦插件获得打包状态解压缩，我想我需要对转换器或解析做一些事情。当它被打包时，插件的第一个字典条目被保存为DataTable。然后，当在Unpack中时，它是带有：分隔符的值中的实际dataTable。

我会提供屏幕截图，但我还没弄明白该怎么做。我想念的任何想法？谢谢！

Answer 1

保存项目时，ProjMngr获取打包的pluginStates字典。我遍历pluginStates字典中的每个字典（插件）并创建一个包含键，值（json字符串版本）和键，值（.net类型）的字典。将这些数组添加到数组中，并将数组放入序列化的最终projectState字典中。这是代码。

signaller.RaiseSaveRequest(pluginStates);  <----has all plugin's packedState

//loop through plugins to get values and types
Dictionary<string, object> dictProjectState = new Dictionary<string, object>();

foreach (KeyValuePair<string,IDictionary<string,object>> plugin in pluginStates)
{ 
    //holds jsonRepresented values
    Dictionary<string, object> dictJsonRep = new Dictionary<string, object>(); 
    //holds object types
    Dictionary<string, object> dictObjRep = new Dictionary<string, object>(); 
    object[] arrayDictHolder = new object[2];  //holds all of the dictionaries

    string pluginKey = plugin.Key;

    IDictionary<string, object> pluginValue = new Dictionary<string, object>(); 
    pluginValue = plugin.Value;

    foreach (KeyValuePair<string, object> element in pluginValue)
    {
      string jsonRepresentation = JsonConvert.SerializeObject(element.Value);
      object objType = element.Value.GetType();
      dictJsonRep.Add(element.Key, jsonRepresentation);
      dictObjRep.Add(element.Key, objType);
    }
    arrayDictHolder[0] = dictJsonRep;
    arrayDictHolder[1] = dictObjRep;
    dictProjectState.Add(pluginKey, arrayDictHolder);
}

JsonSerializer serializer = new JsonSerializer();

using (StreamWriter sw = new StreamWriter(strPathName))
using (JsonWriter writer = new JsonTextWriter(sw))
{
    serializer.Serialize(writer, dictProjectState);
}

然后当一个项目被打开时，我反过来做了同样的事情，让pluginState回到原来的状态，发送到每个插件。使用该类型以确保在发送之前类型是正确的。意识到我必须多次反序列化，这是令人惊讶的。我无法摆脱Jarray或Jobject。但这很有效。这是我打开的方式。

IDictionary<string, IDictionary<string, object>> pluginStates = new Dictionary<string, IDictionary<string, object>>();

StreamReader sr = new StreamReader(fullName);
JsonTextReader reader = new JsonTextReader(sr);
string json = sr.ReadToEnd();

var dictProjectState = JsonConvert.DeserializeObject<Dictionary<string, object>>(json);
sr.Close();
reader.Close();

foreach (var projectStatePair in dictProjectState)
{
    string pluginKey = projectStatePair.Key; //key in pluginStates dict
    Dictionary<string, object> dictJsonRep = new Dictionary<string, object>();
    Dictionary<string, object> dictObjRep = new Dictionary<string, object>();
    Dictionary<string, object> pluginValues = new Dictionary<string, object>();

    string stpluginValue = projectStatePair.Value.ToString();

    Newtonsoft.Json.Linq.JArray ja = (Newtonsoft.Json.Linq.JArray)JsonConvert.DeserializeObject(stpluginValue);

    object[] arrayHolder = ja.ToObject<object[]>();

    string strArray0 = arrayHolder[0].ToString();
    string strArray1 = arrayHolder[1].ToString();

    dictJsonRep = JsonConvert.DeserializeObject<Dictionary<string, object>>(strArray0);
    dictObjRep = JsonConvert.DeserializeObject<Dictionary<string, object>>(strArray1);

    foreach (var pair in dictJsonRep)
    {
         string strVariableKey = pair.Key;
         object objType = dictObjRep[pair.Key];
         string jsonRep = (string)pair.Value;
         Type jsonType = Type.GetType(objType as string);
         object jsonReprValue = null;
         jsonReprValue = JsonConvert.DeserializeObject(jsonRep, jsonType);
         pluginValues.Add(strVariableKey, jsonReprValue);
    }
    pluginStates.Add(pluginKey, pluginValues);
}

signaller.UnpackProjectState(pluginStates);

希望这有助于任何寻找答案的人。

Json.net反序列化包含值为dataTable的字典的字典

1 个答案: