How can I use a List<> as the condition for my where clause with Linq?

Question

So I've been banging my head against the proverbial wall for a few hours and I thought I'd see if anybody else has solved this problem before...

I have a List<string> of values that I want to use as filters on a search. In the olden days I would build a string of WHERE field = 'a' OR field = 'b' OR field = 'C' into the query. But with Linq building that long WHERE clause is rather difficult. What I was hoping would work was:

var results = from x in x.table
              where x.Equals(List<string>)
              select x;

Alas, the compiler isn't smart enough to break down the List<> into a WHERE field = 'a' OR field ='b'kind of query. I've moved ahead with this process as a foreach loop on the List<string> but it's pushing processing to the client when I want that part of the execution to take place on the SQL Server. Am I living in fantasy land here or is there a way to make this happen?

Answer 1

You can use Contains()

List<string> yourList = new List<string> { "A", "B", "C" };

var results = from x in x.table
              where yourList.Contains(x)
              select x;

If it's Linq to SQL it will generate a WHERE field IN ('A', 'B', 'C') clause.