Question

In the database I have 3 tables, User, Group and a lookup table UserGroup which contains UserID and GroupId.

I create a model.edmx and this allows me to:
var users = context.User
var groups = context.Group
but does not create an object for context.UserGroup.

what is the syntax for getting all the users in a group, and all the groups that a user belongs to?

var results = from groups in db.Groups.Where(t => t.Users(u => u.UserID ==1))
select groups;

Answer 1

If you have the proper keys setup, EF will hide away your junction table, and create a navigation property to make the connection between the tables

For getting all the groups a user belongs to:

var groupResults = db.Groups.Where(g => g.Users.Select(u => g.UserId).Contains(userId));

and for getting all the Users:

var userResults = db.Users.Where(u => u.Groups.Select(g => g.GroupId).Contains(groupId));