使用has_many:through时如何访问rails连接模型属性

class User< ApplicationRecord
  has_many :memberships
  has_many :groups, through: :memberships
end

class Group< ApplicationRecord
  has_many :memberships
  has_many :users, through: :memberships
end

class Membership< ApplicationRecord
  belongs_to :user
  belongs_to :group
end

# 获取用户的所有角色
user.memberships.map(&:role)

# 获取用户在特定组中的角色
group = Group.find(group_id)
user_role = user.memberships.find_by(group: group).role