Entity Framework .Where nested in .Include

Question

I\'m attempting to perform a db lookup using EF5 code-first. The basic structure and table relationships are as follows;

public partial class Member
{
    pu         


        

Answer 1

The short answer is no, EF will not let you do that using Include().

Think about the result if it let you do this: in one case your MemberLink.MasterMember.ReceivedMessages will be fully populated, on another identical looking object MemberLink.MasterMember.ReceivedMessages is actually a sub-set of messages! What happens if you try to add to the ReceivedMessages? What if the addition doesn't match the filter? It is a bag of hurt.

The answer is to use projections:

public IList<MemberLinkWithFiltereredMessages> GetMasterLinks(int p_MemberID)
{
    return Get()
        .Include(memberLink => memberLink.MasterMember)
        .Include(memberLink => memberLink.SlaveMember)
        .Where(memberLink => memberLink.MasterMember.RecordID == p_MemberID)
        .Select(memberLink => new MemberLinkWithFilteredMessages
        {
            MemberLink = memberLink,
            FilteredMessages = memberLink.MasterMember.ReceivedMessages
                .Where(msg => msg.Sender.RecordID == memberLink.SlaveMember.RecordID)
        })
        .ToList();
}

What you are really doing is asking for a specific sub-set of information, so be explicit about it.