How do you add dynamic 'where' clauses to a linq query?

Question

I\'ve got a User table with a bitmask that contains the user\'s roles. The linq query below returns all the users whose roles include 1, 4 or 16.

var users          


        

Answer 1

Assuming your UserRoles values are themselves bitmasks, would something like this work?

private List GetUsersFromRoles(uint[] UserRoles) {
    uint roleMask = 0;
    for (var i = 0; i < UserRoles.Length;i++) roleMask= roleMask| UserRoles[i];
    // roleMasknow contains the OR'ed bitfields of the roles we're looking for

    return (from u in dc.Users where (u.UserRolesBitmask & roleMask) > 0) select u);
}

There's probably a nice LINQ syntax that'll work in place of the loops, but the concept should be the same.