Rails未定义方法'has_many'

Question

我正在制作一个数据库：

class CreateUsers < ActiveRecord::Migration
  def change
    has_many :listings, :dependent => :restrict #won't delete if listings exist
    has_many :transactions, :dependent => :restrict #won't del if trans exist
    create_table :users do |t|
      t.integer :key #it's hard to use string as primary
      t.string :identifier_url
      t.string :username
      t.integer :rating

      t.timestamps
    end
  end
end

和

class CreateListings < ActiveRecord::Migration
  def change
    has_one :book
    belongs_to :transaction
    belongs_to :user
    create_table :listings do |t|
      t.integer :key
      t.integer :condition
      t.decimal :price

      t.timestamps
    end
  end
end

我在任何地方都找不到任何相关内容，所以我猜这是非常基本的东西。

Answer 1

您不必在迁移中声明关联，而是在模型中声明关联！