Json.net deserializing list gives duplicate items

Question

I have just started using Newtonsoft.Json (Json.net). In my first simple test, I ran into a problem when deserializing generic lists. In my code sample below I serialize an obje

Answer 1

That is because you are adding items in the constructor. A common approach in deserializers when processing a list is basically:

• read the list via the getter
  • if the list is null: create a new list and assign via the property setter, if one
• deserialize each item in turn, and append (Add) to the list

this is because most list members don't have setters, i.e.

public List Items {get {...}} // <=== no set

Contrast to arrays, which must have a setter to be useful; hence the approach is usually:

• deserialize each item in turn, and append (Add) to a temporary list
• convert the list to an array (ToArray), and assign via the setter

Some serializers give you options to control this behavior (others don't); and some serializers give you the ability to bypass the constructor completely (others don't).