Question

我在RoR中创建一个项目并在运行“rake db：migrate”时出错：

Mysql2::Error: Key column 'item_id' doesn't exist in table

我不明白我做错了什么：

这是我的物品迁移

class CreateMerchants < ActiveRecord::Migration
   def change
       create_table :merchants do |t|
           t.string     :name,      null: false, limit: 100
           t.string     :address,   null: false, limit: 200

           t.timestamps
       end
   end
 end

我的购买迁移：

class CreatePurchases < ActiveRecord::Migration
  def change
    create_table :purchases do |t|
        t.references    :purchasers,        null: false
        t.references    :items,             null: false
        t.references    :merchants,         null: false
        t.decimal       :purchase_count,    null: false, precision: 17, scale: 2

        t.timestamps
    end

    add_index       :purchases,     :item_id
    add_index       :purchases,     :merchant_id
    add_index       :purchases,     :purchaser_id
  end
end

有人可以告诉我我错在哪里吗？

Answer 1

试试这个：

class CreatePurchases < ActiveRecord::Migration
  def change
    create_table :purchases do |t|
        t.integer    :purchaser_id,        null: false
        t.integer    :item_id,             null: false
        t.integer    :merchant_id,         null: false
        t.decimal    :purchase_count,      null: false, precision: 17, scale: 2

        t.timestamps
    end

    add_index       :purchases,     :item_id
    add_index       :purchases,     :merchant_id
    add_index       :purchases,     :purchaser_id
  end
end

Answer 2

问题是引用需要一个单数名称，您也可以在创建引用的同一行中创建索引，因此迁移应该如下所示：

class CreatePurchases < ActiveRecord::Migration
  def change
    create_table :purchases do |t|
        t.references    :purchaser,        null: false, index: true
        t.references    :item,             null: false, index: true
        t.references    :merchant,         null: false, index: true
        t.decimal       :purchase_count,   null: false, precision: 17, scale: 2

        t.timestamps
    end
  end
end

在rails 4.1.4迁移中添加索引ruby

2 个答案: