Entity Framework exclude records from the foreign table

Question

I'm having a problem excluding the records from a foreign table based on a condition.

// this query returns everything from all the tables that are referenced in MainTable

    var query = db.MainTable.Where(x => x.ID == 123)

How can I exclude some of the records from one of the foreign tables based on a Status field in the foreign table? Something like this:

    var query = db.MainTable.Where(x => x.ID == 123 && y => y.ForeignTable.Status == false)

Thank you.

Answer 1

Since you said that you do have the correct relationships set up, and your example seems to suggest that what you have is a singular relationship (not a reference to an ICollection) you should be able to just do:

var query = db.MainTable.Where(x => x.ID == 123 && x.ForeignTable.Status == false) .

If you were using an ICollection, you'd then have to do something like this:

var query = db.MainTable.Where(x => x.ID == 123 && x.ForeignTable.All(y => y.Status == false))

which I think would work, but haven't tested.

You could also look into the Enumerable.Join syntax which I have needed for some more complex joins. It can be really verbose however, and for simple joins the method above should work just fine.