ruby-on-rails - rails : Multiple references to the same model error

Question

我有一个Message 模型，它有一个user 和一个teammember(两者都是用户)。模型是:

# message.rb
class Message < ActiveRecord::Base
  belongs_to :user
  belongs_to :teammember, :class_name => "User", :foreign_key => 'teammember_id' 
end

# user.rb
class User < ActiveRecord::Base
  has_many :messages
end

我有这个迁移:

class CreateMessages < ActiveRecord::Migration
  def change
    create_table :messages do |t|
      t.references :user, index: true, foreign_key: true
      t.references :teammember, index: true, foreign_key: true
      t.text :body
      t.boolean :read, default: false

      t.timestamps null: false
    end
  end
end

当我在本地(使用 sqlite3)运行 rake db:migrate 时，一切正常。问题是当我部署到 heroku(使用 postgresql)并运行

heroku run rake db:migrate

它引发下一个错误:

PG::UndefinedTable: ERROR: relation "teammembers" does not exist : ALTER TABLE "messages" ADD CONSTRAINT "fk_rails_7efc67ccc9" FOREIGN KEY ("teammember_id") REFERENCES "teammembers" ("id")

您知道问题出在哪里吗？我该如何解决？

Answer 1

Rails 根据关联进行猜测，因为您正在引用一个表，它无法从关联中确定您必须自己添加它。

class CreateMessages < ActiveRecord::Migration
  def change
    create_table :messages do |t|
      t.references :user, index: true, foreign_key: true
      t.references :teammember, index: true
      t.text :body
      t.boolean :read, default: false

      t.timestamps null: false
    end
    add_foreign_key :messages, :users, column: :teammember_id
  end
end