c# - How to do an "in" query in entity framework?

Question

How can I do a select in linq to entities to select rows with keys from a list? Something like this:

var orderKeys = new int[] { 1, 12, 306, 284, 50047};
var orders = (from order in context.Orders 
              where (order.Key in orderKeys) 
              select order).ToList();
Assert.AreEqual(orderKeys.Count, orders.Count);

I tried using the Contains method as mentioned in some of the answers but it does not work and throws this exception:

LINQ to Entities does not recognize the method 'Boolean Contains[Int32](System.Collections.Generic.IEnumerable`1[System.Int32], Int32)' method, and this method cannot be translated into a store expression.

Answer 1

Try this:

var orderKeys = new int[] { 1, 12, 306, 284, 50047};
var orders = (from order in context.Orders 
              where orderKeys.Contains(order.Key);
              select order).ToList();
Assert.AreEqual(orderKeys.Count, orders.Count);

Edit: I have found some workarounds for this issue - please see WHERE IN clause?:

The Entity Framework does not currently support collection-valued parameters ('statusesToFind' in your example). To work around this restriction, you can manually construct an expression given a sequence of values using the following utility method: