php - 外键相关的 Laravel 5 迁移错误

Question

这是通过使用包含以下内容的 SQL 转储移植旧项目来学习 Laravel(特别是 v5.x)的尝试:

CREATE TABLE IF NOT EXISTS `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `locationid` int(11) NOT NULL,
  `username` varchar(45) CHARACTER SET latin1 COLLATE latin1_general_ci NOT NULL,
  `email` varchar(200) CHARACTER SET latin1 COLLATE latin1_general_ci NOT NULL,
  `firstname` varchar(100) NOT NULL,
  `lastname` varchar(100) NOT NULL,
  `password` varchar(255) NOT NULL,
  `active` bit(1) DEFAULT b'1',
  `token` varchar(100) DEFAULT NULL,
  `token_created` timestamp NULL DEFAULT NULL,
  `role` varchar(45) NOT NULL DEFAULT 'user',
  `created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  UNIQUE KEY `email_UNIQUE` (`email`),
  UNIQUE KEY `username_UNIQUE` (`username`),
  KEY `location_idx` (`locationid`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=4 ;

在转储的底部有这个与这个特定的表相关:

ALTER TABLE `user`
  ADD CONSTRAINT `location_userfk` FOREIGN KEY (`locationid`) REFERENCES `location` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION;

来自几个 stackoverflow 问题 1 , 2 , 3 ;我修改了我的原始代码，将 Schema::table 的外键从 Schema::create 中分离出来，并将 unsigned() 添加到每个字段:

public function up()
{
    Schema::create('users', function(Blueprint $table)
    {
        $table->increments('id');
        $table->integer('locationid')->unsigned();
        // $table->foreign('locationid')->references('id')->on('location');
        $table->string('username', 60)->unique();
        $table->string('email', 200)->unique();
        $table->string('firstname', 100);
        $table->string('lastname', 100);
        $table->string('password', 255);
        $table->boolean('active')->default(TRUE);
        $table->string('role', 45)->default('user');
        // $table->string('token', 255)->nullable()->default(NULL);
        // $table->string('token_create')->nullable()->default(NULL);
        $table->rememberToken();
        $table->timestamps();
    });

    Schema::table('users', function(Blueprint $table) 
    {
        $table->foreign('locationid')->references('id')->on('location');
    });
}

但是我在使用新创建的空数据库进行迁移时仍然出现错误:

exception 'PDOException' with message 'SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint' in /home/vagrant/projects/communityfuturesbc/vendor/laravel/framework/src/Illuminate/Database/Connection.php:358
Stack trace:
#0 /home/vagrant/projects/communityfuturesbc/vendor/laravel/framework/src/Illuminate/Database/Connection.php(358): PDOStatement->execute(Array) etc...

Next exception 'Illuminate\Database\QueryException' with message 'SQLSTATE[HY000]: General err
or: 1215 Cannot add foreign key constraint (SQL: alter table `users` add constraint users_loca
tionid_foreign foreign key (`locationid`) references `location` (`id`))' in /home/vagrant/proj
ects/communityfuturesbc/vendor/laravel/framework/src/Illuminate/Database/Connection.php:614   
Stack trace:                                                                                  
#0 /home/vagrant/projects/communityfuturesbc/vendor/laravel/framework/src/Illuminate/Database/Connection.php(570): Illuminate\Database\Connection->runQueryCallback('alter table `us...', Ar
ray, Object(Closure))

根据MySQL意思是:

Error: 1215 SQLSTATE: HY000 (ER_CANNOT_ADD_FOREIGN)
Message: Cannot add foreign key constraint                                         

之后，我无法回滚或再次迁移，而不会出现关于数据库中已存在用户表的另一种类型的错误，因此每次我尝试上述代码的一个版本时，我每次都会删除我的数据库。

我确定在修复此问题后，它会出现在所有其他表中，这些表相似或具有多个外键，因此希望无论修复此问题对其余表都有效。

Answer 1

您必须更改迁移顺序

|-database/
|--migrations/
|---2015_02_02_141725_create_users_table.php
|---2015_03_01_234626_create_locations_table.php

应该是:

|-database/
|--migrations/
|---2015_01_01_234626_create_locations_table.php
|---2015_02_02_141725_create_users_table.php

最后:

php artisan migrate