使用反序列化后无法强制转换 json.net 字典中的对象

本文关键字:net json 字典 对象 转换 反序列化 | 更新日期: 2023-09-27 18:33:38

我在反序列化字典方面有问题。我无法将字典中的对象转换为我的类型 Remiza...我正在使用 Json.net,我可以看到字典中的对象是 JObject 而不是对象,我无法将它们转换为我的类型。这是我的序列化/反序列化代码:

    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;
        }

执行:

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

我的问题是,当投射到"Remiza"时,我有这个例外:

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'.

感谢您的任何帮助!

使用反序列化后无法强制转换 json.net 字典中的对象

这应该允许您将 JObect 转换为您的 Remiza 类型。

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

我从下面链接中的堆栈溢出答案中得到了这个。 如果我放的东西不起作用,请查看链接,它应该可以帮助您运行它。

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

为了使用 Json.NET 成功序列化和反序列化多态类型,您需要设置 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);
    }
}

现在,当字典包含 Remiza 的实例时,您应该能够序列化和反序列化字典。

这将适用于序列化为对象或集合的类型。 但是,如果您的字典包含序列化为 JSON 基元的类型(例如 enumlong),则可能需要将它们封装在类型包装器中,就像在 Json.Net 中将特定枚举反序列化为 system.enum 一样。

(顺便说一下,您的_ekstensje字典不是线程安全的。