Json.NET Ignore null values in dictionary

Question

When serializing a dictionary with JSON.NET, it seems like the NullValueHandling setting is ignored.

var dict = new Dictionary<string, string>
{
    ["A"] = "Some text",
    ["B"] = null
};

var json = JsonConvert.SerializeObject(dict, Formatting.Indented,
    new JsonSerializerSettings
    {
        NullValueHandling = NullValueHandling.Ignore
    });

Console.WriteLine(json);

Output:

{
  "A": "Some text",
  "B": null
}

I expected that only the KVP with key "A" is present in the json output and KVP "B" is omitted.

How can I tell Json.NET to only serialize the entries that do not contain null values?

Answer 1

I would just filter out the null values from the original dictionary with LINQ and serialize the filtered dictionary:

using System;
using System.Collections.Generic;
using System.Linq;
using Newtonsoft.Json;

namespace JsonSerialize {
    public static class Program {
        private static Dictionary<string, string> dict = new Dictionary<string, string> {
            ["A"] = "Some text",
            ["B"] = null
        };

        public static void Main(string[] args) {
            var filtered = dict
                .Where(p => p.Value != null)
                .ToDictionary(p => p.Key, p => p.Value);

            var json = JsonConvert.SerializeObject(filtered, Formatting.Indented);

            Console.WriteLine (json);
        }
    }
}

Which gives:

{
  "A": "Some text"
}