I've got a table "Events" with a linked table "Registrations", and I want to create an OData service that returns records from the Events table, plus the number of registrations for each event. The data will be consumed client-side in JavaScript, so I want to keep the size of the returned data down and not include all linked registration records completely.
For example:
ID Title Date Regs
1 Breakfast 01.01.01 12:00 4
2 Party 01.01.01 20:00 20
I'm building the service with ASP.NET MVC4. The tables are in an MSSQL database. I am really just getting started with OData and LINQ.
I tried using the WebAPI OData system first (using classes of EntitySetController) but was getting cryptic server errors as soon as I included the Registrations table in the entity set. ("The complex type 'Models.Registration' refers to the entity type 'Models.Event' through the property 'Event'.")
I had more success building a WCF OData system, and can request event information and information on related registrations.
However, I have no clue how to include the aggregate count information in the event result set. Do I need to create a custom entity set that will be the source for the OData service? I probably included too litte information here for finding a solution, but I don't really know where to look. Can somebody help me?
What I ended up doing was actually very simple; I created a View in SQL Server that returns the table including the registration counts. Never thought about using a view, since I've never used them before...