Question

我连接了模型product和cart_item。

add_reference :cart_items, :product, null: false, foreign_key: true

schema.rb：

  create_table "cart_items", force: :cascade do |t|
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.bigint "product_id", null: false
    t.bigint "cart_id", null: false
    t.index ["cart_id"], name: "index_cart_items_on_cart_id"
    t.index ["product_id"], name: "index_cart_items_on_product_id"
  end

但是当我尝试创建并引用模型属性时，出现错误：

undefined method `product' for #<CartItem:0x0000563873ac8a30>
Did you mean?  product_id

 a = CartItem.new
 a.product_id = 5
 a.cart_id = 1
 a.save
 a.product.title
 #NoMethodError (undefined method `product' for #<CartItem:0x00007ff110f96b50>) Did you mean?  product_id
a.product_id #=> 5

Answer 1

根据您共享的信息，我相信您只是在模型类中添加了Db迁移，但未添加ORM（ActiveRecord）关联。

class CartItem
  ...
  belongs_to :product #Hope you have a model named 'Product'
  ...
end

我相信添加以上行应该可以解决该错误。

为什么我不能吸引相关的模型属性？

1 个答案: