Question

I’m having a problem with a LINQ to SQL query, the data being returned from the server could be null so I’ve set up an if statement within the query but the query is still throwing an exception.

This is a shortened down version of the query code

var a = from b in db.branches
        where (b.Location != null) ?
        (
            (Query.Location == null) ?
                true :
                //The following line causes the exception to be thrown
                object.Equals(Query.Location.ToLower() , b.Location.ToLower())
        ) : 
        (
            (Query.Location == null) ?
                true :
                false
       )
       select b;

If the search term “Location” is null then I don’t want to filter by location, but if it isn’t null then I have to check if the value in the row is null or not as some of entries have a null location.

The code works fine until I add in the compare line. In order to get to the compare line, both Query.Location and b.Location cannot be null therefore the code shouldn’t fail.

Any idea what the problem could be?

Thanks.

EDIT

If i remove the .toLower() from the object.equals call then the query runs correctly, it also manages to work no matter what case the query is in.

var a = from b in db.branches
        where (b.Location != null) ?
        (
            (Query.Location == null) ?
                true :
                //The following line causes the exception to be thrown
                object.Equals(Query.Location , b.Location)
        ) : 
        (
            (Query.Location == null) ?
                true :
                false
       )
       select b;

Answer 1

I wouldn’t like to say for sure what’s going wrong here, but I think you could actually make your code significantly simpler by splitting it into two different queries:

public void Search(SearchTerms Query)
{
    var queryWithLocation = db.branches.Where(b =>
          Query.Location.Equals(b.Location, StringComparison.OrdinalIgnoreCase);

    var query = Query.Location != null ? queryWithLocation : db.branches;
}

I’ve changed the way of doing the Equals – that’s the way I prefer to perform case-insensitive searches; you’ll have to see whether it works for LINQ to SQL.