EntityFunctions.TruncateTime and unit tests

Question

I\'m using System.Data.Objects.EntityFunctions.TruncateTime method to get date part of a datetime in my query:

if (searchOptions.Date.HasValue)
         


        

Answer 1

Although I like the answer given by Smaula using the EntityExpressions class, I think it does a bit too much. Basically, it throws the entire entity at the method, does the compare, and returns a bool.

In my case, I needed this EntityFunctions.TruncateTime() to do a group by, so I had no date to compare to, or bool to return, I just wanted to get the right implementation to get the date part. So I wrote:

private static Expression> GetSupportedDatepartMethod(DateTime date, bool isLinqToEntities)
    {
        if (isLinqToEntities)
        {
            // Normal context
            return () => EntityFunctions.TruncateTime(date);
        }
        else
        {
            // Test context
            return () => date.Date;
        }
    } 

In my case, I did not need the interface with the two seperate implementations, but that should work just the same.

I wanted to share this, because it does the smallest thing possible. It only selects the right method to get the date part.