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Entity Framework Code First 4.3 / LINQKit Predicate for Linked Table

I am using Entity Framework 4.3.1 with the Code First approach. In addition, I use LinqKit to use PredicateBuilder.

If I have tables like:

Location, TimeZone (many: 1)

.. and I want to have something like this:

Expression<Func<TimeZone, bool>> pred = PredicateBuilder.True<TimeZone>();
pred = pred.And(tz => tz.TimeZoneCode == "EST");

List<Location> locations = context.Locations
    .AsExpandable().Where(pred)
    .Select(loc => loc).ToList();

This does not work because the predicate is built to accept TimeZone, but the Where () method gets the location.

I can rewrite the predicate in the same way, but I don’t want to, because I want to have a factory predicate that creates predicates for certain types (I don’t want to use the Navigator properties this way):

Expression<Func<Location, bool>> pred = PredicateBuilder.True<Location>();
pred = pred.And(loc => loc.TimeZone.TimeZoneCode == "EST");

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:

var subPredicate = PredicateBuilder.True<TimeZone>();
subPredicate = subPredicate.And(tz => tz.TimeZoneCode == "EST");

var predicate = PredicateBuilder.True<Location>();
predicate = predicate.And(l => subPredicate.Invoke(l.TimeZone));

List<Location> locations = context.Locations
    .AsExpandable().Where(pred.Expand())
    .Select(loc => loc).ToList();
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+1

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