LINQ Where in collection clause

Question

I've been looking on google but not finding anything that does the trick for me.

as you know SQL has a "where x in (1,2,3)" clause which allows you to check against multiple values. I'm using linq but I can't seem to find a piece of syntax that does the same as the above statement.

I have a collection of category id's (List) against which I would like to check

I found something that uses the .contains method but it doesn't even build.

Answer 1

You have to use the Contains method on your id list:

var query = from t in db.Table
            where idList.Contains(t.Id)
            select t;

Answer 2

The syntax is below:

IEnumerable<int> categoryIds = yourListOfIds;

var categories = _dataContext.Categories.Where(c => categoryIds.Contains(c.CategoryId));

The key thing to note is that you do the contains on your list of ids - not on the object you would apply the in to if you were writing sql.