ruby-on-rails - Rails 中的迁移(sqlite)

Question

嘿，我的 rake 有一个小问题

class CreateEvents < ActiveRecord::Migration

  def self.up
    create_table :events do |t|
      t.integer :broadcast_id
      t.integer :position
      t.string :title
      t.string :location
      t.string :link
      t.text :description
      t.datetime :time
  end
    add_foreign_key :events, :broadcast_id, :broadcasts
  end

  def self.down
    remove_foreign_key :events, :broadcast_id, :broadcasts
    drop_table :events
  end

end

问题 => add_foreign_key :events, :broadcast_id, :broadcasts

$ rake db:迁移

== CreateEvents: migrating ===================================================
-- create_table(:events)
-> 0.0021s
-- add_index(:events, :broadcast_id)
-> 0.0004s
rake aborted!
An error has occurred, this and all later migrations canceled:

SQLite3::SQLException: near "FOREIGN": syntax error: ALTER TABLE "events" ADD FOREIGN KEY ("broadcast_id") REFERENCES "broadcasts"(id)

Answer 1

你为什么要这样定义外键？

如果你想要你的 Events 之间的关系和 Broadcasts那么你应该考虑创建一个事件记录关系。就像是

# Event model
class Event < ActiveRecord::Base
  belongs_to :broadcast
end

# Broadcast model
class Broadcast < ActiveRecord::Base
  has_many :events
end

这样，您就可以让 rails 为您维护外键关系。查看 Rails Guide有关事件记录关联的更多信息。