rewriting SQL query in rails ActiveRecord language ?

Is there any way to write this working query :"DISTINCT `admins`.*").joins("LEFT OUTER JOIN `admins_roles` ON `admins_roles`.`admin_id` = `admins`.`id`").joins("LEFT OUTER JOIN `roles` ON `admins_roles`.`role_id` = `roles`.`id`").where("roles.resource_type IS NULL AND = ?", "manager")

in Rails ActiveRecord "dialect" ?

I tried ( Admins and Roles are associated w an HMABT association

Admin.joins(:roles).where(:roles => {:resource_type => "", :name => :manager}) this doesn't work

If I only write : Admin.joins(:roles).where(:roles => {:name => :manager}) this works, but I get all ;manager with any resource_type

thanks for feedback

just SOLVED it ... :resource_type => "" is wrong should be :resource_type => nil, I'll change my glasses