Asp.Net MVC4 Web API - Return OData formatted Json

I am trying to use the new WebAPI beta to build a web service that I can query using the OData query string conventions and have it return OData formatted Json. I also want to use OData 2.0 (instead of 1.0).

While it doesn't look like it has support for the $select option and headers seem to be able to override the $format option, returning an IQueryable generic seems to provide support for most other query options that I need.

What I am really struggling with is how best to provide Json objects that meet the OData 2.0 specification. WebAPI just returns normal Json data when queried. For example, if I perform a GET request of something like this...

http://localhost:XXXXX/vendor/?$filter=RONUMBER eq '2597385'&$select=VENDORID,VENDORNAME&$top=1&$format=Json

..to get the top hit matching the specified RONumber on my dev machine, I get a response containing the following Json...

[{"MEPartNumber":"11-2222-3-4444","MFGPartNumber":"123456-123","MFGSerialNumber":"ABC123","RONumber":"987654321","VendorId":"1234567","VendorName":"ACME SERVICE CENTER"}]

I need Json that meets the OData 2.0 spec. Something more like this..

OData V2: { 
  "d" : { 
    "results":  { 
        "__metadata": {
            "uri": "http://someserver/foo/vendor(1)",
            "type": "Vendor"
        },
        "MEPartNumber": "11-2222-3-4444",
        "MFGPartNumber": "123456-123",
        "MFGSerialNumber": "ABC123", 
        "RONumber":"987654321", 
        "VendorId":"1234567", 
        "VendorName": "ACME SERVICE CENTER"
    }
  }
}

I suppose I could write a custom MediaTypeFormatter to get the structure that I want. I might also be able to modify my returned objects to mimic the structure of the desired Json. Aside from these two options, does anyone know of a clever way to make WebAPI give me OData 2.0 formatted Json objects?

You need to write your own MediaTypeFormatter to provide the right serialization. We didn't ship an OData formatter in the MVC 4 Beta, but the previous incarnation of WCF Web Api has some examples of how to write one. http://wcf.codeplex.com/SourceControl/list/changesets Look for Microsoft.Net.Http.Formatting.OData (you should be able to use most of the source, though some implementation details might've changed)

An alternative would be to try to construct a DTO that would serialize to the shape expected by OData v2.