Laravel 6.x处理透视表的正确方法

// 定义第一个模型
class User extends Model
{
    public function roles()
    {
        return $this->belongsToMany(Role::class);
    }
}

// 定义第二个模型
class Role extends Model
{
    public function users()
    {
        return $this->belongsToMany(User::class);
    }
}

php artisan make:migration create_role_user_table --create=role_user

public function up()
{
    Schema::create('role_user', function (Blueprint $table) {
        $table->unsignedBigInteger('role_id');
        $table->unsignedBigInteger('user_id');
        $table->timestamps();

        $table->foreign('role_id')->references('id')->on('roles')->onDelete('cascade');
        $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
    });
}

$user = User::find(1);
$roles = $user->roles;

$role = Role::find(1);
$users = $role->users;

$user = User::find(1);
$user->roles()->attach($roleId);

$user = User::find(1);
$user->roles()->detach($roleId);

$user = User::find(1);
$user->roles()->sync([$roleId1, $roleId2]);