Ruby datamapper - search in flag value

Question

I have a user table (datamapper model) that has a column called permission which contains the bitmask value.

property :permission, Flag[:perm1, :perm2, :perm3]

I want to find all the users who have certain permissions, such as perm1 and perm2

so I call,

User.all(:permission => [:perm1, :perm2])

This makes query

select * from user where permission = 3 that is incorrect. while correct query should have been (because it is type - flag)

select * from user where permission &1 != 0 and permission &2 != 0

Does anyone in ruby datamapper, how to make the call to search in flag values.

Answer 1

I could not find any direct way to do it. So did use this hack.

User.all(:conditions => ['permission & ? != 0 and permission & ? != 0', 1,2])

Answer 2

Which version are you running? Under 1.2, I get SELECT ... FROM "users" WHERE "permission" IN (1, 2) ... with User.all(:permission => [:perm1, :perm2]).

One option is to make a union: User.all(:permission => :perm1) | User.all(:permission => :perm2).

Or maybe shortened to User.perm1s | User.perm2s by class methods:

class User
  # ...
  def self.perm1s; all :permission => :perm1 end
  def self.perm2s; all :permission => :perm2 end
end

Not exactly the same query with either one as you've shown, but the result should be the same.