MySQL + Rails：errno：150“外键约束不正确地形成” [英] MySQL + Rails: errno: 150 "Foreign key constraint is incorrectly formed"

问题描述

我试图迁移我的Rails MySQL数据库，我得到以下错误：

I am trying to migrate my Rails MySQL database and I am getting the following error:

ActiveRecord :: StatementInvalid：Mysql2 ::错误：无法创建表开发。注释（错误号：150外键约束未正确形成）： CREATE TABLE 注释（ id int AUTO_INCREMENT PRIMARY KEY，注释 varchar（255）， user_id int， post_id int， created_at datetime NOT NULL， updated_at datetime NOT NULL，INDEX index_comments_on_user_id （ user_id ），INDEX index_comments_on_post_id （ post_id ），CONSTRAINT fk_rails_03de2dc08c
FOREIGN KEY（ user_id ）
REFERENCES 用户（ id ）
，CONSTRAINT fk_rails_2fd19c0db7
FOREIGN KEY（ post_id ）
REFERENCES posts （ id ）
）ENGINE = InnoDB

ActiveRecord::StatementInvalid: Mysql2::Error: Can't create table development.comments (errno: 150 "Foreign key constraint is incorrectly formed"): CREATE TABLE comments (id int AUTO_INCREMENT PRIMARY KEY, comment varchar(255), user_id int, post_id int, created_at datetime NOT NULL, updated_at datetime NOT NULL, INDEX index_comments_on_user_id (user_id), INDEX index_comments_on_post_id (post_id), CONSTRAINT fk_rails_03de2dc08c FOREIGN KEY (user_id) REFERENCES users (id) , CONSTRAINT fk_rails_2fd19c0db7 FOREIGN KEY (post_id) REFERENCES posts (id) ) ENGINE=InnoDB

以下是我的迁移：

class CreateUsers < ActiveRecord::Migration[5.0]
  def change
    create_table :users do |t|
      t.string :first_name
      t.string :last_name
      t.string :linkedin_username
      t.string :facebook_username
      t.string :facebook_id
      t.string :profile_image
      t.string :title_image
      t.string :connection
      t.boolean :team
      t.boolean :active
      t.boolean :admin
      t.string :email
      t.string :password_digest

      t.timestamps
    end
  end
end    

class CreateComments < ActiveRecord::Migration[5.0]
  def change
    create_table :comments do |t|
        t.string :comment
        t.references :user, foreign_key: true
        t.references :post, foreign_key: true
      t.timestamps
    end
  end
end

class CreateCategories < ActiveRecord::Migration[5.0]
  def change
    create_table :categories do |t|
        t.string :name
      t.text :description

      t.timestamps null: false
    end
  end
end

class CreatePosts < ActiveRecord::Migration[5.0]
  def change
    create_table :posts do |t|
        t.string :title
      t.string :description
      t.references :category, foreign_key: true
      t.references :user, foreign_key: true
    end
  end
end

我会非常感谢有人能给我一个想法这里。我一直在谷歌搜索解决方案一段时间，但没有找到任何与此相关的Rails。谢谢！

I would be very thankful if someone could give me an idea here. I have been googling for solutions for a while now but could not find anything on this related to Rails. Thank you!

推荐答案

我刚才找到了这个问题的答案。我的错误是相关的事实，我的帖子表迁移最后。我的注释表迁移引用了post表id父字段。一旦我重新生成注释表迁移并删除了以前的注释表迁移，一切都很好。

I just found the answer to this question. My error was related to the fact that my posts table migration came last. My comments table migration was referencing the post table id parent field. As soon as I regenerated the comment table migration and deleted the previous comment table migration, everything worked out fine.

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