如何在 rails activerecord 中播种 sqlite3 数据库？答案

【问题标题】：How do I seeds sqlite3 data base in rails activerecord?如何在 rails activerecord 中播种 sqlite3 数据库？
【发布时间】：2021-07-22 17:56:39
【问题描述】：

我正在尝试使用以下代码通过 rails ActiveRecord 中 sqlit3 db 上的 seed.rb 文件填充飞行表：

   departure = Date.new(2021, 9, 1)
   arrival = Date.new(2021, 10, 1)

  (departure).upto(arrival).each do |flight_schedule|
   airports.each do |origin|
    airports.each do |destination|
      if origin == destination
        next
      else
        3.times { Flight.create(origin: origin,
                                destination: destination,
                                flight_schedule: flights_time,
                          duration: flights_duration(origin.code, destination.code))}
      end
     end
    end
   end

我在机场和飞行模型之间建立了多对多关系，引用（foreign_key）如下；

class Airport < ApplicationRecord
    has_many :departures, 
             class_name: :Flight, 
             foreign_key: :origin_id, 
             dependent: :destroy

    has_many :arrivals, 
             class_name: :Flight,  
             foreign_key: :destination_id, 
             dependent: :destroy
end

class Flight < ApplicationRecord
  belongs_to :origin, class_name: :Airport
  belongs_to :destination, class_name: :Airport
  
end

这是数据库架构；

ActiveRecord::Schema.define(version: 2021_07_21_232515) do

  create_table "airports", force: :cascade do |t|
    t.string "code"
    t.string "location"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
  end

  create_table "flights", force: :cascade do |t|
    t.integer "origin_id", null: false
    t.integer "destination_id", null: false
    t.integer "duration"
    t.datetime "flight_schedule"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.index ["destination_id"], name: "index_flights_on_destination_id"
    t.index ["origin_id"], name: "index_flights_on_origin_id"
  end

  add_foreign_key "flights", "destinations"
  add_foreign_key "flights", "origins"
end

当我运行 rails db:seed 我有这些错误：

Rails aborted!
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such table: main.destinations

Rails 版本 6.1.4 Ruby 版本 3.0.1p64（2021-04-05 修订版 0fb782ee38）[x86_64-linux]

【问题讨论】：

标签： ruby-on-rails ruby activerecord

【解决方案1】：

架构看起来不正确，add_foreign_key 应该是这样的

add_foreign_key "flights", "airports", column: "destination_id"
add_foreign_key "flights", "airports", column: "origin_id"

所以我猜你的迁移是不正确的，你应该检查那些迁移相对于添加 references 和 foreign_key 到 flights 表，它应该是这样的：

create_table :flights do |t|
 # ...
 t.belongs_to :origin, null: false
 t.belongs_to :destination, null: false
 # ...
 t.foreign_key :airports, column: :origin_id
 t.foreign_key :airports, column: :destination_id
end

【讨论】：