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 = from u in dc.Users             where ((u.UserRolesBitmask & 1) == 1)                || ((u.UserRolesBitmask & 4) == 4)                || ((u.UserRolesBitmask & 16) == 16)             select u; 

I'd like to rewrite this into the method below to returns all the users from the given roles so I can reuse it:

private List<User> GetUsersFromRoles(uint[] UserRoles) {} 

Any pointers on how to dynamically build my query? Thanks

Answer 1

You can use the PredicateBuilder class.

PredicateBuilder has been released in the LINQKit NuGet package

LINQKit is a free set of extensions for LINQ to SQL and Entity Framework power users.