Serialize List<KeyValuePair<string, string>> as JSON

maryhadalittlelamb picture maryhadalittlelamb · Jan 6, 2017 · Viewed 52.9k times · Source

I'm very new with JSON, please help!

I am trying to serialise a List<KeyValuePair<string, string>> as JSON

Currently:

[{"Key":"MyKey 1","Value":"MyValue 1"},{"Key":"MyKey 2","Value":"MyValue 2"}]

Expected:

[{"MyKey 1":"MyValue 1"},{"MyKey 2":"MyValue 2"}]

I referred to some examples from this and this.

This is my KeyValuePairJsonConverter : JsonConverter

public class KeyValuePairJsonConverter : JsonConverter
{
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        List<KeyValuePair<object, object>> list = value as List<KeyValuePair<object, object>>;
        writer.WriteStartArray();
        foreach (var item in list)
        {
            writer.WriteStartObject();
            writer.WritePropertyName(item.Key.ToString());
            writer.WriteValue(item.Value.ToString());
            writer.WriteEndObject();
        }
        writer.WriteEndArray();
    }

    public override bool CanConvert(Type objectType)
    {
        return objectType == typeof(List<KeyValuePair<object, object>>);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        var jsonObject = JObject.Load(reader);
        var target = Create(objectType, jsonObject);
        serializer.Populate(jsonObject.CreateReader(), target);
        return target;
    }

    private object Create(Type objectType, JObject jsonObject)
    {
        if (FieldExists("Key", jsonObject))
        {
            return jsonObject["Key"].ToString();
        }

        if (FieldExists("Value", jsonObject))
        {
            return jsonObject["Value"].ToString();
        }
        return null;
    }

    private bool FieldExists(string fieldName, JObject jsonObject)
    {
        return jsonObject[fieldName] != null;
    }
}

I am calling it from a WebService method like this

List<KeyValuePair<string, string>> valuesList = new List<KeyValuePair<string, string>>();
Dictionary<string, string> valuesDict = SomeDictionaryMethod();

foreach(KeyValuePair<string, string> keyValue in valuesDict)
{
    valuesList.Add(keyValue);
}

JsonSerializerSettings jsonSettings = new JsonSerializerSettings { Converters = new [] {new KeyValuePairJsonConverter()} };
string valuesJson = JsonConvert.SerializeObject(valuesList, jsonSettings);

Answer

OrcusZ picture OrcusZ · Jan 6, 2017

You can use Newtonsoft and dictionary:

    var dict = new Dictionary<int, string>();
    dict.Add(1, "one");
    dict.Add(2, "two");

    var output = Newtonsoft.Json.JsonConvert.SerializeObject(dict);

The output is :

{"1":"one","2":"two"}

Edit

Thanks to @Sergey Berezovskiy for the information.

You are currently using Newtonsoft, so just change your List<KeyValuePair<object, object>> to Dictionary<object,object> and use the serialize and deserialize method from the package.