Question

I have a function where I get a list of ids, and I need to return the a list matching a description that is associated with the id. E.g.:

public class CodeData
{
    string CodeId {get; set;}
    string Description {get; set;}
}

public List<CodeData> GetCodeDescriptionList(List<string> codeIDs)
    //Given the list of institution codes, return a list of CodeData
    //having the given CodeIds
}

So if I were creating the sql for this myself, I would simply do something like the following (where the in clause contains all the values in the codeIds argument):

Select CodeId, Description FROM CodeTable WHERE CodeId IN ('1a','2b','3')

In Linq to Sql I can’t seem to find the equivalent of the “IN” clause. The best I’ve found so far (which doesn’t work) is:

 var foo = from codeData in channel.AsQueryable<CodeData>()
           where codeData.CodeId == "1" || codeData.CodeId == "2"
           select codeData;

The problem being, that I can’t dynamically generate a list of “OR” clauses for linq to sql, because they are set at compile time.

How does one accomplish a where clause that checks a column is in a dynamic list of values using Linq to Sql?

Answer 1

Use

where list.Contains(item.Property)

Or in your case:

var foo = from codeData in channel.AsQueryable<CodeData>()
          where codeIDs.Contains(codeData.CodeId)
          select codeData;

But you might as well do that in dot notation:

var foo = channel.AsQueryable<CodeData>()
                 .Where(codeData => codeIDs.Contains(codeData.CodeId));