Is there a way in Json.NET serialization to distinguish between “null because not present” and “null because null”?

Question

I\'m working in an ASP.NET webapi codebase where we rely heavily on the automatic support for JSON deserialization of message bodies into .NET objects via JSON.NET.

Answer 1

Looking through the Json.NET source, I found that it supports populating bool properties with a suffix of "Specified" to indicate whether or not the property was included in the data:

class MyClass
{
    public string Field1 { get; set; }

    public Nested Nested { get; set; }
    public bool NestedSpecified { get; set; }
}

class Nested
{
    public string Nested1 { get; set; }
    public string Nested2 { get; set; }
}

Input:

{
  "field1": "my field 1",
  "nested": {
    "nested1": "something",
    "nested2": "else"
  }
}

Resulting instance:

MyClass { Field1="my field 1", Nested=Nested { Nested1="something", Nested2="else" }, NestedSpecified=true }

Input:

{
  "field1": "new field1 value"
}

Resulting instance:

MyClass { Field1="new field1 value", Nested=null, NestedSpecified=false }

Input:

{
  "nested": null
}

Resulting instance:

MyClass { Field1=null, Nested=null, NestedSpecified=true }

I can't find this functionality in the Json.NET documentation but it looks like it has been there since 2010.