Entity Framework error using DefaultIfEmpty()

Question

I have a problem with Entity Framework using the DefaultIfEmpty method. The following query is returning empty when it should return an offer that matches all criteria in the database.

If I remove one or both DefaultIfEmpty method calls it works, but with them it doesn't. I need those to prevend another problem in the query.

When I execute the generated SQL query directly on the database it works and it returns the offer.

I also made an Unit Test reproducing the same example and it also passes so it must be an Entity Framework issue.

Here's the query:

private static Expression<Func<Offer, bool>> AddFilter(Service criteria)
{
        return offer => offer.Restrictions.

        SelectMany(rest => rest.OperatorRange.DefaultIfEmpty(), (rest, alop) => new { Restriction = rest, OperatorRange = alop.Id }).
        Where(alop => criteria.ServiceUseNet == null || alop.OperatorRange.ToUpper() == criteria.ServiceUseNet.ToUpper()).

        SelectMany(rest => rest.Restriction.CallType.DefaultIfEmpty(), (rest, till) => new { Restriction = rest, CallType = till.Id }).
        Any(till => criteria.UseServiceCoverage == null || till.CallType.ToUpper() == criteria.UseServiceCoverage.ToUpper());
}

Answer 1

Change it into two Any calls:

return offer => offer.Restrictions
    .Any(rest
        => rest.OperatorRange
                .Where(alop => criteria.ServiceUseNet == null
                             || alop.OperatorRange.ToUpper() == criteria.ServiceUseNet.ToUpper())
        .Any(till => criteria.UseServiceCoverage == null
                  || till.CallType.ToUpper() == criteria.UseServiceCoverage.ToUpper()));

The predicate is supposed to test whether there are any OperatorRange s (meeting some criteria) having any CallType s meeting some criteria. If there are no OperatorRange s, there won't be any CallType s either, let alone matching CallType s.

In this form, the predicate always returns true or false.