Question

这一定是一个非常普遍的问题。我有这样一个链接的多对多关系：

用户n＆lt; ==＆gt; n角色n＆lt; ==＆gt; n列表

ActiveRecord模型：

class User
  # linking to roles
  has_many :role_assignments
  has_many :roles, :through => :role_assignments
end

class Role
  # linking back to users
  has_many :role_assignments
  has_many :users, :through => :role_assignments

  # linking to lists
  has_many :list_assignments
  has_many :lists, :through => :list_assignments
end

class List
  # linking back to roles
  has_many :list_assignments
  has_many :roles, :through => :list_assignments
end

# ... and the join models:
class RoleAssignment
  belongs_to :role
  belongs_to :user
end

class ListAssignment
  belongs_to :list
  belongs_to :role
end

列表模型中的named_scope或关联是什么，以查找具有所有角色的所有列表，而这些列表又具有特定用户？

任何提示都将不胜感激！

Answer 1

到目前为止，我能想出的最佳解决方案如下：

class List
  has_many :list_assignments
  has_many :roles, :through => :list_assignments

  named_scope :managable_by_user, lambda { |u| 
    role_ids = u.roles.map(&:id)
    {
      :include => [:list_assignments], 
      :conditions => {:list_assignments => {:role_id => role_ids}}
    }
  }
end

链接has_many通过：用户 - ＆gt;角色 - ＆gt;名单。查找分配给用户的列表（通过角色）

1 个答案: