通过Rails在has_many上添加附加属性

Question

我已经建立了以下关联：

class BookLaunch < ApplicationRecord
  has_many :book_launch_locations, dependent: :destroy
  has_many :stores, through: :book_launch_locations
    
....

class Store < ApplicationRecord

  has_many :book_launch_locations
  has_many :book_launch, through: :book_launch_locations

....

class BookLaunchLocation < ApplicationRecord
  belongs_to :book_launch, :touch => true
  belongs_to :store
end

BookLaunchLocation有一个名为book_price的属性。

  create_table "book_launch_locations", id: :integer, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8", force: :cascade do |t|
    t.integer "book_launch_id", null: false
    t.integer "store_id", null: false
    t.integer "book_price", default: 1, null: false
    ...
    t.index ["book_launch_id", "store_id"], name: "pair_uniqueness", unique: true
    t.index ["book_launch_id"], name: "index_book_launch_locations_on_book_launch_id"
    t.index ["store_id"], name: "index_book_launch_locations_on_store_id"
  end 

我想将book_price添加到BookLaunch模型中的商店，这样当我调用@book_launch.stores时，它将拥有商店的所有属性+ book_price属性。

这个是可能的吗？

我使用fastJsonApi命名它，如下所示：

    options = {
      include: [:book_launch, :'book_launch.properties']}
    json = Api::launchSummarySerializer.new(summaryData, options).serialized_json

    render json: json

Answer 1

如果您想创建一个只包含两个以上外键列的连接模型行，则需要显式地而不是隐式地创建它。

store = Store.first
book_launch = BookLaunch.first

BookLaunchLocation.create(
  store: store,
  book_launch: book_launch,
  price: 999
)

# or
store.book_launch_locations.create(
  book_launch: book_launch,
  price: 999
)

# or
book_launch.book_launch_locations.create(
  store: store,
  price: 999
)

隐式创建联接模型行是在您通过间接关联创建它时：

Store.first.book_launches.create!(attributes)
BookLaunch.first.stores.create!(attributes)