Question

我想在我的项目中建立多态关联，所以我跟着rails指南去做，但我得到了：minimal superkey 错误。

型号：

DashboardAssignment：

NameError: uninitialized constant DashboardAssignment::Assignable

用户：

class DashboardAssignment < ActiveRecord::Base
  belongs_to :dashboard
  belongs_to :assignable, polymorphic: true

  validates :dashboard, presence: true
  validates :assignable, presence: true, uniqueness: { :scope => :dashboard }
end

组：

class User < ActiveRecord::Base
  has_many :dashboard_assignments, as: :assignable
  has_many :dashboards, through: :dashboard_assignments
end

控制板：

class Group < ActiveRecord::Base
  has_one :dashboard_assignment, as: :assignable
  has_many :laboratories_assignments, as: :lab_assignable
end

在DashboardAssignment 迁移文件中，我有：

class Dashboard < ActiveRecord::Base
  has_one :building
  has_many :dashboard_assignments
  has_many :users, through: :dashboard_assignments, as: :assignable
end

当我尝试t.references :assignable, null: false, polymorphic: true, index: true DashboardAssignment.create(assignable: u)时创建新的DashboardAssignment 它给了我错误：

u = User.find(1)

我做错了吗？

我的rails版本 4.2.6

Answer 1

您应该在source关联中使用as而不是through

class Dashboard < ActiveRecord::Base
  has_one :building
  has_many :dashboard_assignments
  has_many :users, through: :dashboard_assignments, source: :assignable
end

我会提醒您，这可能会为您assignables提供类Group。解决此问题的最佳方法是为has_many的{{1}}添加一个条件，让您仅对dashboard_assignments dashboard_assignments的{{1}}进行过滤：

assignable_type = 'User'

Rails'未初始化的常数'错误中的多态性

1 个答案: