Question

I have the following method in a service, please note the .user on the def usersByRole line:

def getUsersByRole(String desiredRole1, String desiredRole2, String desiredRole3) {
    Role role1 = Role.findByAuthority(desiredRole1)
    Role role2 = Role.findByAuthority(desiredRole2)
    Role role3 = Role.findByAuthority(desiredRole3)
    def usersByRole = UserRole.findAllByRoleInList([role1, role2, role3]).user
    return usersByRole
}  

It works good, but when a user has multiple roles (i.e. ROLE_ADMIN, and ROLE_OWNER) then that user exists twice in the collection if both of the previously mentioned roles are given as parameters. Is there any clean way I can make the collection contain only unique results?

Answer 1

A similar question as yours can be found here: GORM createCriteria and list do not return the same results : what can I do?

Method 1

If you want to return unique list of users directly from DB query then you can use listDistinct on User (supposing that user has a roles OneToMany association with UserRoles)

User.createCriteria().listDistinct {
    roles {
       in 'role', [role1, role2, role3]
    }
}

Method 2

You can also try to query UserRole directly and group by User using the groupProperty (see http://www.grails.org/doc/latest/ref/Domain%20Classes/createCriteria.html)

Method 3

Remove duplicated users from the returned list:

UserRole.findAllByRoleInList([role1, role2, role3])*.user.unique()