Method GetById and SingleResult

Question

Here is my method that I use to get one entity in an ASP.NET Web API application.

[EnableQuery]
public virtual HttpResponseMessage GetById([FromODataUri]int id)
{
    // get concrete entity from repository
    var entity = repository.GetById(id);
   // check entity
    if (entity == null)
    {
        var message = string.Format("No {0} with ID = {1}", GenericTypeName, id);
        return ErrorMsg(HttpStatusCode.NotFound, message);
    }

    // problem
    return Request.CreateResponse(HttpStatusCode.OK, SingleResult.Create(repository.Table.Where(t => t.ID == id)));
}

I'm using SingleResult for OData request (because $expand for single entity does not work if I do not create SingleResult). But in this case I repeatedly do almost the same action repository.GetById(id); and repository.Table.Where(t => t.ID == id).

How can I improve it?

Answer 1

You can wrap the single entity into an IQueryable. Something like this should work:

SingleResult.Create(new[]{entity}.AsQueryable());

You could write a helper function that uses this trick to convert from a single T to an IQueryable<T>. There may even be a built-in way of doing this.