Question

我有一个派生自Dictionary的类。该类本身也具有ClientId属性。我想使用Json.Net将此类的集合反序列化为JSON字符串所以请遵循文档here

public interface IClientSettings: IDictionary<string, string>
{        
    string ClientId { get; set; }        
}

public class ClientSettings : Dictionary<string, string>, IClientSettings
{        
    public string ClientId { get; set; }
}

然后我将列表反序列化为字符串

        var list = new List<IClientSettings>();

        var client1 = new ClientSettings();
        client1.ClientId = "Client1";
        client1.Add("key1", "value1");
        client1.Add("key2", "value2");
        client1.Add("key3", "value3");

        var client2 = new ClientSettings();
        client1.ClientId = "Client2";
        client2.Add("key1", "value1");
        client2.Add("key2", "value2");
        client2.Add("key3", "value3");

        list.Add(client1);
        list.Add(client2);

        string json = JsonConvert.SerializeObject(list, Formatting.Indented);
        Console.WriteLine(json);

但是，这不会序列化Clientid属性。以下是输出。

[
  {
    "key1": "value1",
    "key2": "value2",
    "key3": "value3"
  },
  {
    "key1": "value1",
    "key2": "value2",
    "key3": "value3"
  }
]

我不确定我在这里缺少什么。我还发现建议自定义序列化的建议here，这是我唯一的选择吗？

Answer 1

是的，你是对的，你需要做一些自定义序列化。如果您标记类型，Json.NET将序列化字典的键/值对作为JSON对象（使用JsonDictionaryContract），或将字典的属性序列化为JSON对象（使用JsonObjectContract）与[JsonObject] - 但不是两者。我怀疑两者都没有实现，从而避免了当字典包含与属性同名的密钥时运行时名称冲突的可能性，例如：

var client3 = new ClientSettings();
client3.ClientId = "Client1";
client3["ClientId"] = "Conflicting Value";

根据IETF standard，

当对象中的名称不唯一时，接收此类对象的软件的行为是不可预测的。

因此，这是最好避免的情况。

一种可能的实施方式如下：

[JsonObject(MemberSerialization = MemberSerialization.OptIn)]
public class ClientSettings : Dictionary<string, string>, IClientSettings
{
    [JsonProperty]
    public string ClientId { get; set; }

    [JsonProperty]
    IDictionary<string, string> Items { get { return new DictionaryWrapper<string, string>(this); } }
}

使用

public class DictionaryWrapper<TKey, TValue> : IDictionary<TKey, TValue>
{
    readonly IDictionary<TKey, TValue> dictionary;

    public DictionaryWrapper(IDictionary<TKey, TValue> dictionary)
    {
        if (dictionary == null)
            throw new ArgumentNullException("dictionary");
        this.dictionary = dictionary;
    }

    #region IDictionary<TKey,TValue> Members

    public void Add(TKey key, TValue value) { dictionary.Add(key, value); }

    public bool ContainsKey(TKey key) { return dictionary.ContainsKey(key); }

    public ICollection<TKey> Keys { get { return dictionary.Keys; } }

    public bool Remove(TKey key) { return dictionary.Remove(key); }

    public bool TryGetValue(TKey key, out TValue value) { return dictionary.TryGetValue(key, out value); }

    public ICollection<TValue> Values { get { return dictionary.Values; } }

    public TValue this[TKey key]
    {
        get { return dictionary[key]; }
        set { dictionary[key] = value; }
    }

    #endregion

    #region ICollection<KeyValuePair<TKey,TValue>> Members

    public void Add(KeyValuePair<TKey, TValue> item) { dictionary.Add(item); }

    public void Clear() { dictionary.Clear(); }

    public bool Contains(KeyValuePair<TKey, TValue> item) { return dictionary.Contains(item); }

    public void CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex) { dictionary.CopyTo(array, arrayIndex); }

    public int Count { get { return dictionary.Count; } }

    public bool IsReadOnly { get { return dictionary.IsReadOnly; } }

    public bool Remove(KeyValuePair<TKey, TValue> item) { return dictionary.Remove(item); }

    #endregion

    #region IEnumerable<KeyValuePair<TKey,TValue>> Members

    public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator() { return dictionary.GetEnumerator(); }

    #endregion

    #region IEnumerable Members

    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return GetEnumerator(); }

    #endregion
}

MemberSerialization.OptIn用于防止序列化Count，Comparer，Keys和Values等基类属性。

有了这个，您的JSON将如下所示：

[
  {
    "ClientId": "Client2",
    "Items": {
      "key1": "value1",
      "key2": "value2",
      "key3": "value3"
    }
  }
]

Json.Net无法序列化从字典派生的类的属性

1 个答案: