JSON Serializer object with internal properties

Question

I have class with some internal properties and I would like to serialize them into json as well. How can I accomplish this? For example

public class Foo {     internal int num1 { get; set; }     internal double num2 { get; set; }     public string Description { get; set; }      public override string ToString()     {         if (!string.IsNullOrEmpty(Description))             return Description;          return base.ToString();     } } 

Saving it using

Foo f = new Foo(); f.Description = "Foo Example"; JsonSerializerSettings settings = new JsonSerializerSettings() { TypeNameHandling = TypeNameHandling.All };   string jsonOutput = JsonConvert.SerializeObject(f, Formatting.Indented, settings);   using (StreamWriter sw = new StreamWriter("json_file.json"))  {      sw.WriteLine(jsonOutput);  } 

I get

{   "$type": "SideSlopeTest.Foo, SideSlopeTest", "Description": "Foo Example" } 

Answer 1

Mark the internal properties to be serialized with the [JsonProperty] attribute:

public class Foo {     [JsonProperty]     internal int num1 { get; set; }     [JsonProperty]     internal double num2 { get; set; }      public string Description { get; set; }      public override string ToString()     {         if (!string.IsNullOrEmpty(Description))             return Description;          return base.ToString();     } } 

And then later, to test:

Foo f = new Foo(); f.Description = "Foo Example"; f.num1 = 101; f.num2 = 202; JsonSerializerSettings settings = new JsonSerializerSettings() { TypeNameHandling = TypeNameHandling.All };  var jsonOutput = JsonConvert.SerializeObject(f, Formatting.Indented, settings);  Console.WriteLine(jsonOutput); 

I get the following output:

{   "$type": "Tile.JsonInternalPropertySerialization.Foo, Tile",   "num1": 101,   "num2": 202.0,   "Description": "Foo Example" } 

(Where "Tile.JsonInternalPropertySerialization" and "Tile" are namespace and assembly names I am using).

As an aside, when using TypeNameHandling, do take note of this caution from the Newtonsoft docs:

TypeNameHandling should be used with caution when your application deserializes JSON from an external source. Incoming types should be validated with a custom SerializationBinder when deserializing with a value other than None.

For a discussion of why this may be necessary, see TypeNameHandling caution in Newtonsoft Json and and External json vulnerable because of Json.Net TypeNameHandling auto?.