How to do a "where in values" in LINQ-to-Entities 3.5

Question

Does anybody know how to apply a "where in values" type condition using LINQ-to-Entities? I've tried the following but it doesn't work:

var values = new[] { "String1", "String2" };  // some string values

var foo = model.entitySet.Where(e => values.Contains(e.Name));

I believe this works in LINQ-to-SQL though? Any thoughts?

Answer 1

Update: found out how to do this. And EF will generate the appropriate SQL on the database. I'm not sure if this is for EF4 only but I got the tip from Entity Framework 4.0 Recipes

---

var listOfIds=GetAListOfIds();
var context=CreateEntityFrameworkObjectContext();
var results = from item in context.Items
              where listOfIds.Contains(item.Category.Id)
              select item;
//results contains the items with matching category Ids

This query generates the correct in clause on the server side. I haven't tested it with EF 3.5 but it does work with EF4.

NB: The values passed into the in clause are NOT parameters so make sure you validate your inputs.

Answer 2

It is somewhat of a shame that Contains is not supported in Linq to Entities.

IN and JOIN are not the same operator (Filtering by IN never changes the cardinality of the query).