我试图在Laravel中创建外键，但是当我使用artisan迁移我的表时，我抛出了以下错误:
[Illuminate\Database\QueryException]
SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint (SQL
: alter table `priorities` add constraint priorities_user_id_foreign foreign
key (`user_id`) references `users` (`id`))
我的迁移代码如下:
优先级迁移文件
public function up()
{
//
Schema::create('priorities', function($table) {
$table->increments('id', true);
$table->integer('user_id');
$table->foreign('user_id')->references('id')->on('users');
$table->string('priority_name');
$table->smallInteger('rank');
$table->text('class');
$table->timestamps('timecreated');
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
//
Schema::drop('priorities');
}
用户迁移文件
public function up()
{
//
Schema::table('users', function($table)
{
$table->create();
$table->increments('id');
$table->string('email');
$table->string('first_name');
$table->string('password');
$table->string('email_code');
$table->string('time_created');
$table->string('ip');
$table->string('confirmed');
$table->string('user_role');
$table->string('salt');
$table->string('last_login');
$table->timestamps();
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
//
Schemea::drop('users');
}
关于我做错了什么，我现在想要得到这个，因为我有很多表，我需要创建例如用户，客户端，项目，任务，状态，优先级，类型，团队。理想情况下，我想创建表持有这些数据与外键，即clients_project和project_tasks等。
希望有人能帮我开始。
我们不能添加关系，除非创建了相关的表。Laravel根据迁移文件的日期顺序运行迁移。因此，如果您想要与第二个迁移文件中存在的表创建关系，则会失败。
我也遇到了同样的问题，所以我最后创建了一个迁移文件来指定所有关系。
Schema::table('properties', function(Blueprint $table) {
$table->foreign('user')->references('id')->on('users')->onDelete('cascade');
$table->foreign('area')->references('id')->on('areas')->onDelete('cascade');
$table->foreign('city')->references('id')->on('cities')->onDelete('cascade');
$table->foreign('type')->references('id')->on('property_types')->onDelete('cascade');
});
Schema::table('areas', function(Blueprint $table) {
$table->foreign('city_id')->references('id')->on('cities')->onDelete('cascade');
});
拉拉维尔 ^5.8
从Laravel 5.8开始，迁移存根在ID上使用bigIncrements方法
列。方法创建ID列
增量的方法。
这不会影响项目中的任何现有代码;然而,是
注意外键列必须具有相同的类型。因此,一个
使用increments方法创建的列不能引用列
使用bigIncrements方法创建。
来源:Migrations & bigIncrements
例子
假设您正在构建一个简单的基于角色的应用程序，并且需要在PIVOT表“role_user”中引用user_id。
2019年_05_05_112458_create_users_table.php
// ...
public function up()
{
Schema::create('users', function (Blueprint $table) {
$table->bigIncrements('id');
$table->string('full_name');
$table->string('email');
$table->timestamps();
});
}
2019_05_05_120634_create_role_user_pivot_table.php
// ...
public function up()
{
Schema::create('role_user', function (Blueprint $table) {
// this line throw QueryException "SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint..."
// $table->integer('user_id')->unsigned()->index();
$table->bigInteger('user_id')->unsigned()->index(); // this is working
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
});
}
As you can see, the commented line will throw a query exception, because, as mentioned in the upgrade notes, foreign key columns must be of the same type, therefore you need to either change the foreing key (in this example it's user_id) to bigInteger in role_user table or change bigIncrements method to increments method in users table and use the commented line in the pivot table, it's up to you.
I hope i was able to clarify this issue to you.
