老外-删除外键 [英] foreigner - remove foreign key

问题描述

我正在尝试在Rails 4应用程序中使用邮箱程序.当我尝试部署数据库时出现问题.创建邮箱程序对话表时发生错误，该表在通知表中具有依赖性.

I am trying to use mailboxer in my rails 4 app. A problem is arising when i try to deploy the db. The error occurs in creating the mailboxer conversations table, which has dependencies in notifications table.

我正在尝试删除通知对话的外键.

I am trying to remove the foreign key for notifications conversations.

我创建了一个迁移，上面写着:

I created a migration which says:

change_table :notifications do |t|
t.remove_foreign_key :conversations

但是，耙子中止并说不存在外键.

However, the rake aborts and says a foreign key does not exist.

rake aborted!
An error has occurred, this and all later migrations canceled:

PG::UndefinedObject: ERROR:  constraint "notifications_conversation_id_fk" of relation      "notifications" does not exist

我的架构包括: add_foreign_key通知"，对话"，名称:"notifications_on_conversation_id"

My schema includes: add_foreign_key "notifications", "conversations", name: "notifications_on_conversation_id"

我试图使db:migrate:down导致创建邮箱的原始迁移，但还出现一条错误消息，提示找不到命令".

I tried to rake db:migrate:down the original migration that created mailboxer, but also got an error saying 'command not found'.

任何人都可以帮忙吗?谢谢.

Can anyone help? Thank you.

推荐答案

模式中的add_foreign_key命令为您的外键提供了名称notifications_on_conversation_id.此名称不同于外国人通常根据列名称指定的默认名称，该名称为notifications_conversation_id_fk.因此，您的remove_foreign_key命令必须指定现有的外键名称而不是列名称.试试:

The add_foreign_key command in your schema gave your foreign key the name notifications_on_conversation_id. This name is different than the default name that foreigner would normally assign based on the column name, which is notifications_conversation_id_fk. So your remove_foreign_key command must specify the existing foreign key name instead of the column name. Try:

remove_foreign_key :notifications, name: "notifications_on_conversation_id"

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