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

You could add some metadata to your JSON objects and (most likely) DTOs. It would require additional processing, but is pretty transparent and unambiguously accomplishes what you need (assuming you can name the new field such that you know it won't collide with actual data).

{
  "deletedItems": null,
  "field1": "my field 1",
  "nested": {
    "deletedItems": null,
    "nested1": "something",
    "nested2": "else"
  }
}
{
  "deletedItems": "nested",
  "field1": "new value",
  "nested": null
}

Alternatively, you could add an "isDeleted" property per field if your object model accommodates that better, but that sounds like a lot more work than a list of deleted fields.