Question

基于我以前的question，我正在构建一个多态关联。我也希望有一对多的关系。所以我创建了一个新的表/模型posties / Posty来管理这种关系

帖子可以属于多个玩家和多个团队。

型号：

class Posty < ActiveRecord::Base
    belongs_to :posts
    belongs_to :target, :polymorphic => true
end

class Post < ActiveRecord::Base
    has_many :posties
    has_many :players, :through => :posties
end

class Player < ActiveRecord::Base
    has_many :posts,:as => :target, :through => :posties
end

表：

  create_table "posties", id: false, force: true do |t|
    t.integer  "posty_id"
    t.string   "posty_type", limit: 30
    t.integer  "post_id"
  end

  create_table "posts", force: true do |t|
    t.integer  "user_id"
    t.date     "post_date"
    t.string   "title"
  end

  create_table "players", force: true do |t|
    t.string   "name"
  end

当我这样做时，Player.find(1).posts，我得到了

ActiveRecord::HasManyThroughAssociationNotFoundError: Could not find the association :posties in model Player

可能出现什么问题？

Answer 1

你可能可以取消这个中间Posty类，因为只需要连接表/模型来进行多对多关联。除此之外，你需要修复设置。

多态列名称应基于关联名称。

create_table "posties", force: true do |t|
  t.integer  "target_id"
  t.string   "target_type", limit: 30
  t.integer  "post_id"
end

class Posty < ActiveRecord::Base
  belongs_to :post
  belongs_to :target, :polymorphic => true
end

class Post < ActiveRecord::Base
  has_many :posties
  has_many :players, :through => :posties, :as => :target
end

class Player < ActiveRecord::Base
  has_many :posties, :as => :target
  has_many :posts, :through => :posties
end

编辑：

我最好补充一点，这可能仍然无效。我相当肯定你不能拥有has_many虽然是多态关联。在这种情况下，你应该删除Posty类，或者变得非常有创意！

create_table "posts" do |t|
  t.integer  "target_id"
  t.string   "target_type", limit: 30
end

class Post < ActiveRecord::Base
  belongs_to :target, :polymorphic => true
end

class Player < ActiveRecord::Base
  has_many :posts, :as => :target
end

多态关联中的一对多

1 个答案: