php - Laravel 迁移名称太长

Question

我正在尝试迁移整个 Laravel 应用程序，当我编写下面的代码时出现一些错误。

    // Create table for associating permissions to users (Many To Many Polymorphic)
   Schema::create('permission_user', function (Blueprint $table) {
        $table->unsignedInteger('permission_id');
        $table->unsignedInteger('user_id');
        $table->string('user_type');
        $table->unsignedInteger('project_id')->nullable();. 
        $table->foreign('permission_id')->references('id')->on('permissions')
            ->onUpdate('cascade')->onDelete('cascade');
        $table->foreign('project_id')->references('id')->on('projects')
            ->onUpdate('cascade')->onDelete('cascade');
        $table->unique(['user_id', 'permission_id', 'user_type', 'project_id']);
    });

错误:

SQLSTATE[42000]: Syntax error or access violation: 1059 Identifier name 'permission_user_user_id_permission_id_user_type_project_id_unique' is too long (SQL: alter table permission_user add unique permission_user_user_id_permission_id_user_type_project_id_unique(user_id, permission_id, user_type, project_id))`

当我删除上面的代码时，一切正常。怎么了？我没有找到任何东西？!

Answer 1

laravel 生成唯一 key 的方式太长。您可以通过执行

来覆盖它

$table->unique(['user_id', 'permission_id', 'user_type', 'project_id'], 'my_unique_ref');

此外，如果外键太长，您可以覆盖默认名称，但提供第二个参数。

$table->foreign('permission_id', 'my_new_reference')->references('id')->on('permissions')
                ->onUpdate('cascade')->onDelete('cascade');