Derik Whittaker

***** Disclaimer ******
I may be the last person to figure this out, but oh well.
***** End Disclaimer ******

Today as I was further exploring the coolness that is Linq to Sql I ran into a little situation.  I was creating a query where I wanted to use the columns form multiple tables to build an object.  Since the results did not map 1 to 1 from a table to a object I figured I would have to do it the mapping the hard way.  Here was the code I originally had.

var results = from c in DBContextInstance().Companies
              join pc in DBContextInstance().ProgramControls on c.CoID equals pc.CoID
              select new {c.CoID, c.CoDesc, pc.ProjectNotes, pc.ProjectManager};

List newList = new List< HybridObject >();

foreach ( var result in results )
{
    HybridObject entity = new HybridObject
                              {
                                  CompanyID = result.CoID,
                                  CompanyDesc = result.CoDesc,
                                  ProjectNotes = result.ProjectNotes,
                                  ProjectManager = result.ProjectManager
                              };
    newList.Add( entity  );
}

After looking at the code above for a few minutes, I really, really did not like it.  I knew there had to be a better way.  So I started playing around with various ways to do this.  I had a hunch that since I was creating a return value as an Anonymous type, I should be able to create a concrete type in its place.  Sure enough, I could.  With a little help from constructor initializers (sure you could also do this by creating a constructor that took in the values as well).  Take a look at the new, cleaner code below.

var results = ( from c in DBContextInstance().Companies
              join pc in DBContextInstance().ProgramControls on c.CoID equals pc.CoID
              select new HybridObject
                         {
                                CompanyID = CoID,
                                CompanyDesc = CoDesc,
                                ProjectNotes = ProjectNotes,
                                ProjectManager = ProjectManager
                         } ).ToList();

Now if you ask me, the new code is much more concise and much simpler.  It also does not waste CPU cycles, which is always a plus.

If anyone has a better way, please let me know.

Till next time,