How to write this complex LINQ to Entities query

Question

I'm writing an application that will allow our users to send newsletters to their contacts. Here is the database structure (only important fields):

Contacts(tbl)       ContactEmails(tbl)       Newsletters(tbl)
  ContactID           ContactEmailID           NewsletterID
  ...                 ContactID (fk)           ...
                      EmailAddress             
                      Deleted
                      ...


NewsletterLists(tbl)       NewsletterToLists(tbl)
  NewsletterListID           NewsletterID (fk)
  ...                        NewsletterListID (fk)


NewsletterListToContacts(tbl)
  NewsletterListID (fk)
  ContactID (fk)
  Active
  Deleted
  UnsubscribedOn
  ...

Now I have a class structured as:

public class NewsletterContactEmails
{
    public int ContactID { get; set; }
    public List<string> EmailList { get; set; }
}

I want to have a NewsletterContactEmails object for each contact so that I can loop through it and send one email each contact (not each email address).

I have the Newsletter object to start working with. So in pseudo it would be...

1. Get NewsletterLists this newsletter is to send to.
2. Get Active (double opted-in) and non-deleted/unsubscribed DISTINCT Contact List from said NewsletterLists.
3. Create NewsletterContactEmails object for each contact and add their non-deleted DISTINCT list of email addresses.

I want to do this in one query. Here is what I currently have, I think I'm close but this won't even compile:

List<NewsletterContactEmails> Recipients = objNewsletter.NewsletterToLists
                    .Select(ntl => ntl.NewsletterList.NewsletterListToContacts
                        .Where(nl => nl.Active == true && nl.Deleted == false && nl.UnsubscribedOn == null)
                        .Select(nl => new NewsletterContactEmails {
                            ContactID = nl.ContactID,
                            EmailList = nl.Contact.ContactEmails.Where(ce => ce.Deleted == false).Select(ce => ce.EmailAddress).Distinct().ToList()
                        }));

Any help is greatly appreciated!

Answer 1

List<NewsletterContactEmails> Recipients = objNewsletter.NewsletterToLists
    .SelectMany(ntl => ntl.NewsletterList.NewsletterListToContacts
        .Where(nl => nl.Active == true && nl.Deleted == false && nl.UnsubscribedOn == null)
        .Select(nl => new NewsletterContactEmails
        {
            ContactID = nl.ContactID,
            EmailList =
                nl.Contact.ContactEmails.Where(ce => ce.Deleted == false)
                    .Select(ce => ce.EmailAddress)
                    .Distinct()
                    .ToList()
        }));

Try the first select as SelectMany instead of Select