First i suggest to use newton json dll.
Second your need create custom JsonConverter for KeyValuePair<string,int> like this:
public class PairConverter : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return objectType == typeof(KeyValuePair<string, int>);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
throw new NotImplementedException();
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
var item = (KeyValuePair<string, int>)value;
writer.WriteValue(item.Value);
writer.Flush();
}
}
And than add JsonConverter attribute for 'Age' property like this:
public class Persons
{
[JsonConverter(typeof(PairConverter))]
public KeyValuePair<string, int> Age { get; set; }
}
Finally, example of usage:
var persons = new Persons()
{
Age = new KeyValuePair<string, int>("Age", 10)
};
var json = JsonConvert.SerializeObject(persons); // {Age:10}