.net - Why is the Web Api returning empty json results with "$ref="?

Question

I disabled lazy loading and proxy creation in EF5 before returning any results in the Web Api. Everything worked fine. However, when i start to Include() other entities for eager fetching, some of the JSON objects look like this:

{
$ref: "14"
},
.. correct objects ..
{
$ref: "6"
},
..

What is this "$ref" that gets included in the list of results?

Answer 1

It's coming from the JSON.NET serializer. It's preserving object references. Take a look at the following blog post. I guess you have some circular references in your object graph and JSON.NET is doing it's best in a desperate effort to serialize this EF structure without crashing (which is what most JSON serializers would do anyway). It's not a standard though.

Personal advice: never serialize your EF entities. Always define view models and have your Web API methods return view models containing only the properties you are interested in.