如何从ac＃列表中拉出一列？

Question

My code defines an LoginUser object, with a number of columns -- LoginUserId, UserName, ActiveFlag , etc. I have a List<LoginUser> of these objects.

Right now, my code creates a List<int> , then iterates through the List<LoginUser> , inserting each LoginUserId into the List<int> in turn.

Is there a more efficient way to handle this, or some sort of built in function for it?

Answer 1

You can use LINQ:

var userIds = loginUser.Select(l => l.LoginUserId);

Where loginUser is your list of LoginUser objects.

This will generate an IQueryable<int> which you can either enumerate as is or convert to a list (via .ToList() )

Answer 2

Use LINQ

List<int> userIds = (from user in userList
                select user.LoginUserId).ToList();