Rails應用程序中的ForeignKey問題/錯誤

Question

我正在rails中構建一個小型私人購物車，我使用devise進行身份驗證，Postgres使用數據庫。

現在我正在嘗試從我的PG數據庫中刪除用戶，導軌給了我這個錯誤，我現在相當迷茫。

[1] pry(main)> User.destroy_all 
User Load (1.7ms) SELECT "users".* FROM "users" 
(0.8ms) BEGIN 
SQL (7.4ms) DELETE FROM "users" WHERE "users"."id" = $1 [["id", 1]] 
(0.3ms) ROLLBACK 
ActiveRecord::InvalidForeignKey: PG::ForeignKeyViolation: ERROR: update or delete on table "orders" violates foreign key constraint "fk_rails_e3cb28f071" on table "order_items" 
DETAIL: Key (id)=(1) is still referenced from table "order_items". 
: DELETE FROM "users" WHERE "users"."id" = $1 
from /Users/myname/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql_adapter.rb:602:in `exec_prepared' 

從來就更新用戶和訂單表foreignKeys如下

class UpdateForeignKey < ActiveRecord::Migration 
    def change 
    # remove the old foreign_key 
    remove_foreign_key :orders, :users 

    # add the new foreign_key 
    add_foreign_key :orders, :users, on_delete: :cascade 
    end 
end 

遷移文件中看到我試圖從order_item表中刪除外鍵但隨後控制檯給了我這個錯誤

Table 'order_items' has no foreign key on column '_id'/Users/myname/Documents/Vefir/stores/brainstore/db/migrate/20160607140507_update_foreign_key_order_item.rb:4:in `change' 
ArgumentError: Table 'order_items' has no foreign key on column '_id' 
/Users/myname/Documents/Vefir/stores/brainstore/db/migrate/20160607140507_update_foreign_key_order_item.rb:4:in `change' 
Tasks: TOP => db:migrate 
(See full trace by running task with --trace) 

從來就還增加dependent: :destroy到order.rb和user.rb模型，但我不確定如果多數民衆贊成確定。

任何人都可以引導我在這裏的正確方向嗎？我不知道我還能做什麼？

下面

是user.rb，order.rb order_item.rb和schema.rb

user.rb

class User < ActiveRecord::Base 
# Include default devise modules. Others available are: 
# :confirmable, :lockable, :timeoutable and :omniauthable 
devise :database_authenticatable, :registerable, 
    :recoverable, :rememberable, :trackable, :validatable 

    validates_presence_of :name, :address, :city, :country, :postal_code 
end 

order.rb

class Order < ActiveRecord::Base 
belongs_to :user, dependent: :destroy 
has_many :order_items, dependent: :destroy 

def total_price 
    order_items.inject(0) { |sum, item| sum + item.total_price } 
end 
end 

order_item.rb

class OrderItem < ActiveRecord::Base 
    belongs_to :order, dependent: :destroy 
    belongs_to :product, dependent: :destroy 

def total_price 
    self.quantity * self.product.price 
end 
end 

schema.rb

ActiveRecord::Schema.define(version: 20160607135951) do 

# These are extensions that must be enabled in order to support this database 
enable_extension "plpgsql" 

create_table "categories", force: :cascade do |t| 
    t.string "name" 
    t.datetime "created_at", null: false 
    t.datetime "updated_at", null: false 
end 

create_table "category_names", force: :cascade do |t| 
    t.datetime "created_at", null: false 
    t.datetime "updated_at", null: false 
end 

create_table "order_items", force: :cascade do |t| 
    t.integer "order_id" 
    t.integer "product_id" 
    t.integer "quantity" 
    t.datetime "created_at", null: false 
    t.datetime "updated_at", null: false 
end 

add_index "order_items", ["order_id"], name: "index_order_items_on_order_id", using: :btree 
add_index "order_items", ["product_id"], name: "index_order_items_on_product_id", using: :btree 

create_table "orders", force: :cascade do |t| 
    t.integer "user_id" 
    t.datetime "created_at", null: false 
    t.datetime "updated_at", null: false 
end 

add_index "orders", ["user_id"], name: "index_orders_on_user_id", using: :btree 

create_table "products", force: :cascade do |t| 
    t.string "name" 
    t.string "description" 
    t.float "price" 
    t.string "image" 
    t.datetime "created_at",    null: false 
    t.datetime "updated_at",    null: false 
    t.integer "category_id", default: 1 
end 

add_index "products", ["category_id"], name: "index_products_on_category_id", using: :btree 

create_table "users", force: :cascade do |t| 
    t.string "email",     default: "", null: false 
    t.string "encrypted_password",  default: "", null: false 
    t.string "reset_password_token" 
    t.datetime "reset_password_sent_at" 
    t.datetime "remember_created_at" 
    t.integer "sign_in_count",   default: 0, null: false 
    t.datetime "current_sign_in_at" 
    t.datetime "last_sign_in_at" 
    t.inet  "current_sign_in_ip" 
    t.inet  "last_sign_in_ip" 
    t.string "name" 
    t.string "address" 
    t.string "phone" 
    t.string "postal_code" 
    t.string "country" 
    t.string "city" 
    t.datetime "created_at",       null: false 
    t.datetime "updated_at",       null: false 
end 

add_index "users", ["email"], name: "index_users_on_email", unique: true, using: :btree 
add_index "users", ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true, using: :btree 

add_foreign_key "order_items", "orders" 
add_foreign_key "order_items", "products" 
add_foreign_key "orders", "users", on_delete: :cascade 
add_foreign_key "products", "categories" 

末

Answer 1

這個問題的答案是做這樣一次遷移。

class UpdateForeignKeyOrderItem < ActiveRecord::Migration 
def change 
    # remove the old foreign_key 
    remove_foreign_key :order_items, :orders 

    # add the new foreign_key 
    add_foreign_key :order_items, :orders, on_delete: :cascade 
    end 
end