Exception while trying to deserialize JSON into EntityFramework using JavaScriptSerializer

Question

I'm trying to deserialize JSON which I'm getting from an external source into an Entity Framework entity class using the following code:

var serializer = new JavaScriptSerializer();
IList<Feature> obj = serializer.Deserialize<IList<Feature>>(json);

The following exception is thrown:

Object of type 'System.Collections.Generic.List1[JustTime.Task]' cannot be converted to type 'System.Data.Objects.DataClasses.EntityCollection1[JustTime.Task]'.

My model is simple: The Feature class has a one-to-many relation to the Tasks class. The problem appears to be the deserializer is trying to create a generic List to hold the collection of tasks instead of an EntityCollection.

I've tried implementing a JavaScriptConverted which would handle System.Collections.Generic.List but it didn't get called by the deserializer.

Answer 1

You can't assign a list directly to an EF collection. You have to add to it. So deserialize to a POCO and then copy.