用StringComparer反序列化JSON字典

Question

我试图序列化/反序列化一个字典，问题是我用一个StringComparer.OrdinalIgnoreCase比较器创建了字典。

下面是我正在经历的问题的代码片段：

var dict = new Dictionary<string, Dictionary<string, string>>(StringComparer.OrdinalIgnoreCase);

dict["x"] = new Dictionary<string, string>();
dict["x"]["y"] = "something";

var serialized = JsonConvert.SerializeObject(dict);

var unSerialized = JsonConvert.DeserializeObject<Dictionary<string, Dictionary<string, string>>>(serialized);

Console.WriteLine((dict.Comparer == unSerialized.Comparer ? "Same" : "Different"));

(.NET Fiddle -试试看)

在控制台上打印以下内容：

Different

显然，JSON序列化程序没有序列化我在创建字典时设置的比较器，但问题是，由于Dictionary.Comparer是只读的，所以无法在事实之后设置比较器。

我确信这与一些定制的JsonSerializerSetting有关，但我似乎不知道如何截取集合创建，并返回一个具有不同比较器的字典。

Answer 1

还可以使用PopulateObject填充现有对象。

var dict = new Dictionary<string, Dictionary<string, string>>(StringComparer.OrdinalIgnoreCase);

dict["x"] = new Dictionary<string, string>();
dict["x"]["y"] = "something";

var json = JsonConvert.SerializeObject(dict);


var result =  new Dictionary<string, Dictionary<string, string>>(StringComparer.OrdinalIgnoreCase);
JsonConvert.PopulateObject(json, result);

Console.WriteLine(result["x"]["y"]);
Console.WriteLine(result.Comparer == dict.Comparer ? "Same" : "Diff");

输出：

something
Same

Answer 2

如果将反序列化的结果和要使用的比较器传递给新字典的构造函数，则可以在字典的构造函数中指定要使用的比较器：

var deserialized = JsonConvert
    .DeserializeObject<Dictionary<string, Dictionary<string, string>>>(serialized);

var withComparer = new Dictionary<string, Dictionary<string, string>> (
    deserialized, StringComparer.OrdinalIgnoreCase);

Answer 3

现在可能有点晚了，但是使用JsonConverter扩展生成的JSON可能会更复杂，但更灵活。我已经为所描述的案例创建了一个示例，它不是满的

.NET Fiddle -试试看

(如果您决定使用它，请随意扩展)：

public class DictConverter<TValue> : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return true;
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        var obj = JToken.ReadFrom(reader);                
        if (objectType == typeof(Dictionary<string, TValue>))
        {
            var comparer = obj.Value<string>("Comparer");
            Dictionary<string, TValue> result;
            if (comparer == "OrdinalIgnoreCase")
            {
                result = new Dictionary<string, TValue>(StringComparer.OrdinalIgnoreCase);
            }
            else
            {
                result = new Dictionary<string, TValue>();
            }
            obj["Comparer"].Parent.Remove();
            serializer.Populate(obj.CreateReader(), result);
            return result;
        }
        return obj.ToObject(objectType);
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        var obj = JObject.FromObject(value);
        if (value is Dictionary<string, TValue>)
        {
            if((value as Dictionary<string, TValue>).Comparer == StringComparer.OrdinalIgnoreCase)
                obj.Add("Comparer", JToken.FromObject("OrdinalIgnoreCase"));
        }
        obj.WriteTo(writer);

    }
}

和使用

var dict = new Dictionary<string, Dictionary<string, string>>(StringComparer.OrdinalIgnoreCase);

dict["x"] = new Dictionary<string, string>();
dict["x"]["y"] = "something";

var serialized = JsonConvert.SerializeObject(dict, 
    new DictConverter<Dictionary<string,string>>());
var unSerialized = JsonConvert.DeserializeObject<Dictionary<string, Dictionary<string, string>>>
    (serialized, new DictConverter<Dictionary<string, string>>());