LINQ: Split Where OR conditions

Question

So I have the following where conditions

sessions = sessions.Where(y => y.session.SESSION_DIVISION.Any(x => x.DIVISION.ToUpper().Contains(SearchContent         


        

Answer 1

There are a few ways to go about this:

1. Apply the "where" to the original query each time, and then Union() the resulting queries.

   var queries = new List>();
   if (!String.IsNullOrEmpty(Division)) {
       queries.Add(sessions.Where(y => y.session.SESSION_DIVISION.Any(x => x.DIVISION.ToUpper().Contains(SearchContent))));
   }
   
   if (!String.IsNullOrEmpty(Room)) {
   
       // this shoudl be OR
       queries.Add(sessions.Where(y => y.session.ROOM.ToUpper().Contains(SearchContent)));
   }
   
   if (!String.IsNullOrEmpty(course)) {
   
       // this shoudl be OR
       queries.Add(sessions.Where(y => y.session.COURSE.ToUpper().Contains(SearchContent)));
   }
   
   sessions = queries.Aggregate(sessions.Where(y => false), (q1, q2) => q1.Union(q2));
   

2. Do Expression manipulation to merge the bodies of your lambda expressions together, joined by OrElse expressions. (Complicated unless you've already got libraries to help you: after joining the bodies, you also have to traverse the expression tree to replace the parameter expressions. It can get sticky. See this post for details.

3. Use a tool like PredicateBuilder to do #2 for you.