未定义方法的未决迁移错误 - Rails 4

Question

我正在修复我在将数据库 table 中的列类型从整数命名为日期时间时犯的错误。但是，在我运行 rake db:migrate 写完以下内容后，我得到了一个挂起的迁移错误。当我通过 rails g MigrateDeliveryTimeDates 添加新迁移时，db/migrate 下没有生成新文件，所以我手动创建了它。错误内容为：

An error has occurred, this and all later migrations canceled:
undefined method `deliverytime_temp'

这是我的 db/migrate 文件：

class ChangeColumnDeliveryTime < ActiveRecord::Migration
  def change
    rename_column(:deliveries, :deliverytime, :deliverytime_temp)
    add_column(:deliveries, :deliverytime, :datetime)  
  end
end

这是我添加的迁移 (rails g migration ChangeColumnDeliveryTime):

class ChangeColumnDeliveryTime < ActiveRecord::Migration
   def change
   change_column(:deliveries, :deliverytime, :datetime)
  end
end

这是我的数据库模式：

ActiveRecord::Schema.define(version: 20160216220012) do

  create_table "deliveries", force: :cascade do |t|
    t.string   "name"
    t.string   "deliveryaddress"
    t.integer  "deliverytime"
    t.string   "notes"
    t.integer  "order_id"
    t.datetime "created_at",      null: false
    t.datetime "updated_at",      null: false
  end

  add_index "deliveries", ["order_id"], name: "index_deliveries_on_order_id"

  create_table "orders", force: :cascade do |t|
   t.datetime "date"
   t.string   "name"
   t.string   "pickup"
   t.datetime "pickuptime"
   t.datetime "created_at", null: false
   t.datetime "updated_at", null: false
  end
end

我该如何解决这个错误？

Answer 1

您需要使用change_column method instead add_column

def change
  # rename_column :table_name, :old_column_name, :new_column_name
  rename_column :deliveries, :deliverytime, :deliverytime_temp
  change_column :deliveries, :deliverytime_temp, :datetime
  # change_column :table_name, :column_name, :new_data_type
end

未定义方法的未决迁移错误 - Rails 4

Pending migration error for undefined method - Rails 4

ruby

ruby-on-rails

ruby-on-rails-3