Is it possible to use ODataQueryOptions with DTO's?

Question

ContentType --> EF model

ContentTypes --> DTO

In my OData controller:

   public Task<IQueryable<ContentTypes>> Get(ODataQueryOptions<ContentTypes> options) 
   {
        var result = options.ApplyTo(_repository.Query().Get()
            .Where(u => u.UserId == userId)
            .OrderBy(o => o.Description))
            .Cast<ContentTypes>();

        return result;
   }

I get an error 500 when trying to apply the ODataQueryOptions. Since the class already inherits ODataController do I even need to do theoptions.ApplyTo(...)?

Answer 1

The solution for this was to ensure the return type is the the DTO's type, and that the ODataQueryOptions are applied to the EF entity. I then use Automapper to map the result to the DTO.

I have updated the answer based on @Schandlich 's suggestions, however some issues persist:

    [Queryable]
    public virtual IHttpActionResult Get(ODataQueryOptions<ContentType> options)
    {
        var userId = 102;   // mock

        try
        {
            var results = options.ApplyTo(_uow.Repository<ContentType>()
                .Query()
                .Get()
                .Include(u => u.User)
                .Where(u => u.UserId == userId)
                .OrderBy(o => o.Description)).Cast<ContentType>()
                .Select(x => new ContentTypeDTO()
                {
                    //projection goes here
                    ContentTypeId = x.ContentTypeId,
                    Description = x.Description,
                    UserDTO = new UserDTO 
                    { 
                        UserId = x.UserId,
                        UserName = x.User.UserName
                    }
                });

            return this.Ok(results);
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

The reason for using ODataQueryOptions is that I want EF to handle the filtering down at the database call level. Otherwise, I would get all records returned, then the Queryable would kick in to return, say the first page of results.

I removed the Automapper code, but curious as to why not use this?

As @Schandlich pointed out, however, this will not work for $select or $expand.