使用json.net反序列化后無法從Dictionary投射對象

Question

我對反序列化詞典有問題。 我無法將對象從Dictionary轉換為我的類型Remiza ...我正在使用Json.net，而我看到的是Dictionary中的對象不是JObject，而是對象，所以無法將其轉換為我的類型。 這是我的序列化/反序列化代碼：

    private static Dictionary<Type, List<Object>> _ekstensje = new Dictionary<Type, List<Object>>();

    public static void SerializeDictionary()
        {
            string json = JsonConvert.SerializeObject(_ekstensje);
            System.IO.StreamWriter file = new System.IO.StreamWriter(@"c:\tmp\dictionary.json");
            file.WriteLine(json);

            file.Close();
        }

        public static void DeserializeDictionary()
        {
            string json;
            System.IO.StreamReader file = new System.IO.StreamReader(@"c:\tmp\dictionary.json");
            json = file.ReadToEnd();

            file.Close();
            _ekstensje = JsonConvert.DeserializeObject<Dictionary<Type, List<Object>>>(json);//Deserializacja Dictionary
            Debug.WriteLine(_ekstensje);
        }

        public static List<Object> GetEkstensja(Type className)
        {
            List<Object> list = _ekstensje[className];
            return list;
        }

驅逐：

        ObjectPlus.DeserializeDictionary();
        List<Object> list = ObjectPlus.GetEkstensja(typeof(Remiza));
        foreach (Object o in list)
        {
            Remiza r = (Remiza) o;
            listaRemiz.Add(r);
        }

我的問題是當投射到“ Remiza”時，我有一個例外：

An exception of type 'System.InvalidCastException' occurred in Osek_MAS_WPF.exe but was not handled in user code. Additional information: Unable to cast object of type 'Newtonsoft.Json.Linq.JObject' to type 'Osek_MAS_WPF.Remiza'.

謝謝你的幫助！

Answer 1

這應該允許您將JObect轉換為Remiza類型。

ObjectPlus.DeserializeDictionary();
    List<Object> list = ObjectPlus.GetEkstensja(typeof(Remiza));
    foreach (Object o in list)
    {
        Remiza r = o.ToObject<Remiza>();
        listaRemiz.Add(r);
    }

我是從下面鏈接的stackoverflow答案中得到的。 如果我輸入的內容無效，請查看鏈接，它應該可以幫助您使其正常運行。

https://stackoverflow.com/a/10221594/634769

Answer 2

為了使用Json.NET成功序列化和反序列化多態類型，您需要設置TypeNameHandling = TypeNameHandling.Auto ，如下所示：

public class ObjectPlus
{
    // Replace with whatever file name is appropriate.  My computer doesn't have a "c:\tmp" directory.
    static string JsonFileName { get { return Path.Combine(Path.GetTempPath(), "dictionary.json"); } }

    static JsonSerializerSettings JsonSettings { get { return new JsonSerializerSettings { TypeNameHandling = TypeNameHandling.Auto, Formatting = Formatting.Indented }; } }

    private static Dictionary<Type, List<Object>> _ekstensje = new Dictionary<Type, List<Object>>();

    public static void SerializeDictionary()
    {
        var path = JsonFileName;

        using (var stream = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.Read))
        using (var writer = new StreamWriter(stream))
        {
            var serializer = JsonSerializer.CreateDefault(JsonSettings);
            serializer.Serialize(writer, _ekstensje);
        }
    }

    public static void DeserializeDictionary()
    {
        var path = JsonFileName;
        try
        {
            using (var stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
            using (var reader = new StreamReader(stream))
            using (var jsonReader = new JsonTextReader(reader))
            {
                var serializer = JsonSerializer.CreateDefault(JsonSettings);
                _ekstensje = serializer.Deserialize<Dictionary<Type, List<Object>>>(jsonReader);
            }
        }
        catch (FileNotFoundException)
        {
            // File was not created yet, dictionary should be empty.
            _ekstensje.Clear();
        }
    }

    public static List<Object> GetEkstensja(Type className)
    {
        List<Object> list = _ekstensje[className];
        return list;
    }

    public static void AddEkstensja<T>(T obj)
    {
        List<Object> list;
        if (!_ekstensje.TryGetValue(obj.GetType(), out list))
            list = _ekstensje[obj.GetType()] = new List<object>();
        list.Add(obj);
    }

    internal static string ShowJsonContents()
    {
        if (!File.Exists(JsonFileName))
            return string.Empty;
        return File.ReadAllText(JsonFileName);
    }
}

現在，當字典包含Remiza實例時，您應該可以序列化和反序列化字典。

這適用於序列化為對象或集合的類型。 但是，如果您的字典包含序列化為JSON原語的類型（例如， enum或long 整數），則可能需要按照將特定枚舉反序列化到Json.Net中的system.enum的方式將它們封裝在類型包裝器中 。

（順便說一句，您的_ekstensje詞典不是線程安全的。）