“Cannot call methods on DateTime”, and other limitations

Question

Does anyone know of a definitive list of LINQ to SQL query limitations that are not trapped at compile time, along with (where possible) workarounds for the limitations?

Answer 1

I had exactly this issue with DateTimes, and found that currently the following workaround works for me, but I realise that with larger result sets, it could get to be an issue as the processing is now in my app rather than on the database:

BlogPosts post = (from blogs in blogPosts
           where blogs.PostPath == path 
           select blogs)
           .ToList()
           .Where(blogs => blogs.Published.Date == publishedDate.Date)
           .SingleOrDefault();

Note the ".ToList()" in the middle - this casts it to a normal IEnumerable and allows me to use the usual properties I'd expect.

One thing that still confuses me slightly however is the fact that this is legal in EF:

BlogPosts posts = from blogs in blogPosts
           where !blogs.IsDraft
             && blogs.Published.Year == year
             && blogs.Published.Month == month
           orderby blogs.Published descending
           select blogs

So, I can call ".Year" or ".Month" on a DateTime, but not ".Date" - I guess it comes down to types.