JSON.NET反序列化Tuple <...>另一種類型不起作用？

Question

使用Json.net，反序列化包含Tuple<...>不工作類型（串行化的作品，但反序列化不）：

[TestMethod] 
public void Test() 
{ 
    var orig = new TupleHolder("what????", true); 
    var json = JsonConvert.SerializeObject(orig); 
    Assert.AreEqual("{\"Tup\":{\"Item1\":\"what????\",\"Item2\":true}}", json); 
    // great! serialization works like a charm! now let's test deserialization: 
    var dupl = JsonConvert.DeserializeObject<TupleHolder>(json); 

    Assert.AreEqual("ZZZ", dupl.Tup.Item1); // pass! but it should be "what????"... what???? 
    Assert.AreEqual(false, dupl.Tup.Item2); // pass! but it should be "true", right??? 

    Assert.AreEqual(orig.Tup.Item1, dupl.Tup.Item1); // fail! 
    Assert.AreEqual(orig.Tup.Item2, dupl.Tup.Item2); // fail! 
} 

public class TupleHolder 
{ 
    public Tuple<string, bool> Tup { get; set; } 
    public TupleHolder() { Tup = new Tuple<string, bool>("ZZZ", false); } 
    public TupleHolder(string s, bool b) { Tup = new Tuple<string, bool>(s, b); } 
} 

有趣的是，Tuple<...>直接反序列化沒有問題：

[TestMethod] 
public void Test2() 
{ 
    var orig = new Tuple<string, bool>("ABC", true); 
    var json = JsonConvert.SerializeObject(orig); 
    var dupl = JsonConvert.DeserializeObject<Tuple<string, bool>>(json); 
    Assert.AreEqual(orig, dupl); // direct deserialization of Tuple<...> works. 
} 

是Json.NET錯誤還是我在這裏丟失的東西？

Answer 1

無論如何，解決方案或我的解決方案都是爲Tuple定義一個自定義轉換器。

這個例子爲特定的元組提供了一個具體的解決方案，但是你可以通用化它來使TupleConverter類處理任何值類型的組合。也可以使其變爲抽象並且派生類型爲每個項目實現實例化方法，以處理具有參考類型的元組。

public class TupleConverter : Newtonsoft.Json.JsonConverter 
    { 
     public override bool CanConvert(Type objectType) 
     { 
      return typeof(Tuple<string, bool>) == objectType; 
     } 

     public override object ReadJson(
      Newtonsoft.Json.JsonReader reader, 
      Type objectType, 
      object existingValue, 
      Newtonsoft.Json.JsonSerializer serializer) 
     { 
      if (reader.TokenType == Newtonsoft.Json.JsonToken.Null) 
       return null; 

      var jObject = Newtonsoft.Json.Linq.JObject.Load(reader); 

      var target = new Tuple<string, bool>(
       (string)jObject["Item1"], (bool)jObject["Item2"]); 

      return target; 
     } 

     public override void WriteJson(Newtonsoft.Json.JsonWriter writer, object value, Newtonsoft.Json.JsonSerializer serializer) 
     { 
      serializer.Serialize(writer, value); 
     } 
    } 

    public class TupleHolder 
    { 
     [Newtonsoft.Json.JsonConverter(typeof(TupleConverter))] 
     public Tuple<string, bool> Tup { get; set; } 
     public TupleHolder() { Tup = new Tuple<string, bool>("ZZZ", false); } 
     public TupleHolder(string s, bool b) { Tup = new Tuple<string, bool>(s, b); } 
    } 

    [Test] 
    public void Test() 
    { 
     var orig = new TupleHolder("what????", true); 
     var json = Newtonsoft.Json.JsonConvert.SerializeObject(orig); 

     Assert.AreEqual("{\"Tup\":{\"Item1\":\"what????\",\"Item2\":true}}", json); 

     var dupl = Newtonsoft.Json.JsonConvert.DeserializeObject<TupleHolder>(json); 

     // These succeed, now 
     Assert.AreEqual(orig.Tup.Item1, dupl.Tup.Item1); 
     Assert.AreEqual(orig.Tup.Item2, dupl.Tup.Item2); 
    } 

Answer 2

Remi提供的答案幫助了我。我拿了他的TupleConverter，並將它作爲一個2元組的通用。這個概念對於任何N元組都是一樣的。

我把它留在這裏是爲了幫助別人。

public class TupleConverter<U, V> : Newtonsoft.Json.JsonConverter 
{ 
    public override bool CanConvert(Type objectType) 
    { 
     return typeof(Tuple<U, V>) == objectType; 
    } 

    public override object ReadJson(
     Newtonsoft.Json.JsonReader reader, 
     Type objectType, 
     object existingValue, 
     Newtonsoft.Json.JsonSerializer serializer) 
    { 
     if (reader.TokenType == Newtonsoft.Json.JsonToken.Null) 
      return null; 

     var jObject = Newtonsoft.Json.Linq.JObject.Load(reader); 

     var target = new Tuple<U, V>(
      jObject["m_Item1"].ToObject<U>(), jObject["m_Item2"].ToObject<V>()); 

     return target; 
    } 

    public override void WriteJson(Newtonsoft.Json.JsonWriter writer, object value, Newtonsoft.Json.JsonSerializer serializer) 
    { 
     serializer.Serialize(writer, value); 
    } 
} 

注：我的元組是JSON序列與m_Item1和m_Item2，所以我不得不改變jObject["ItemX"]到jObject["m_ItemX"]

使用例如與List<Tuple<int, User>>：

string result = "String to deserialize"; 
JsonSerializerSettings settings = new JsonSerializerSettings(); 
settings.Converters.Add(new TupleConverter<int, User>()); 
List<Tuple<int, User>> users = JsonConvert.DeserializeObject<List<Tuple<int, User>>>(result, settings);