在null上调用成员函数isCollection（）

Question

我，使用Graphaware Neo4j-php-OGM。我想访问二级关系。我无法看到让它发挥作用。我究竟做错了什么？

我正在尝试执行以下操作：

public function allowToContinue($userUuid, $permissionUuid)
    {
        $userRepo = $this->entityManager->getRepository(User::class);
        $permRoleRepo = $this->entityManager->getRepository(PermRole::class);
        $permissionRepo = $this->entityManager->getRepository(Permission::class);
        $user = $userRepo->findOneBy(['uuid' => $userUuid]);
        $permission = $permissionRepo->findOneBy(['uuid' => $permissionUuid]);
        $allowed = false;
        foreach ($user->getPermrole() as $userRole)
        {
            var_dump($userRole);
            $role = $permRoleRepo->findOneBy(['uuid' => $userRole->getUuid()]);
            var_dump($role);
            foreach ($role->getPermissions() as $perm)
            {
                var_dump($perm->getUuid());
                if($perm->getUuid() === $permissionUuid){
                    $allowed = true;
                }
            }
        }
        return $allowed;
    }

堆栈跟踪：

Error:
Call to a member function isCollection() on null

  at vendor/graphaware/neo4j-php-ogm/src/Hydrator/EntityHydrator.php:107
  at GraphAware\Neo4j\OGM\Hydrator\EntityHydrator->hydrateSimpleRelationshipCollection('permissions', object(Result), object(neo4j_ogm_proxy_App_Entity_Generic_PermRole))
     (vendor/graphaware/neo4j-php-ogm/src/Persisters/BasicEntityPersister.php:104)
  at GraphAware\Neo4j\OGM\Persisters\BasicEntityPersister->getSimpleRelationshipCollection('permissions', object(neo4j_ogm_proxy_App_Entity_Generic_PermRole))
     (vendor/graphaware/neo4j-php-ogm/src/Proxy/NodeCollectionInitializer.php:22)
  at GraphAware\Neo4j\OGM\Proxy\NodeCollectionInitializer->initialize(object(Node), object(neo4j_ogm_proxy_App_Entity_Generic_PermRole))
     (vendor/graphaware/neo4j-php-ogm/src/Proxy/LazyCollection.php:52)
  at GraphAware\Neo4j\OGM\Proxy\LazyCollection->doInitialize()
     (vendor/doctrine/collections/lib/Doctrine/Common/Collections/AbstractLazyCollection.php:332)
  at Doctrine\Common\Collections\AbstractLazyCollection->initialize()
     (vendor/doctrine/collections/lib/Doctrine/Common/Collections/AbstractLazyCollection.php:274)
  at Doctrine\Common\Collections\AbstractLazyCollection->getIterator()
     (src/Security/RoleChecker.php:45)
  at App\Security\RoleChecker->allowToContinue('8d88d920-5ab0-11e8-a371-001c42dff143', 'd93370b0-585d-11e8-a371-001c42dff143')
     (src/Controller/Generic/UserController.php:146)
  at App\Controller\Generic\UserController->destroy('c34f1380-5ab5-11e8-a371-001c42dff143')
     (vendor/symfony/http-kernel/HttpKernel.php:149)
  at Symfony\Component\HttpKernel\HttpKernel->handleRaw(object(Request), 1)
     (vendor/symfony/http-kernel/HttpKernel.php:66)
  at Symfony\Component\HttpKernel\HttpKernel->handle(object(Request), 1, true)
     (vendor/symfony/http-kernel/Kernel.php:188)
  at Symfony\Component\HttpKernel\Kernel->handle(object(Request))
     (public/index.php:37)

它会在第二个foreach循环上引发错误：

foreach ($role->getPermissions() as $perm)

这很奇怪，第一次正确工作而不是第二次。此外，再次获取对象后，确保。没有它，它会抛出完全相同的通知。提前致谢！

所有代码都在github：https://github.com/djkevino/Support4Neo

Answer 1

老实说，这段代码非常困惑。 var_dump() die()中的destroy()内容...另外，我花了一段时间才意识到我们正在讨论库中的代码，而不是与此库交互的代码。

你能避免这样的问题吗？

//add this next line
if (!is_iterable($user->getPermrole())) continue;
foreach ($role->getPermissions() as $perm)

如果您不使用PHP 7.1或更高版本，您只需检查返回值is_null或测试instance of \Traversable和is_array ...

is_array($foo) || (is_object($foo) && ($foo instanceof \Traversable ));

如我的评论中所述，不确定没有“权限”的角色是否被视为有效状态。

Answer 2

1. 看起来$ role-> getPermissions（）可以返回null结果。因此，在执行内部null循环之前，请确保结果不是foreach。
2. 由于您似乎在测试用户的任何角色是否具有所需的权限，因此您根本不需要$allowed变量。一旦发现匹配，内部foreach循环可以立即返回true，避免不必要的处理。

也就是说，试试这个：

public function allowToContinue($userUuid, $permissionUuid) {
    $userRepo = $this->entityManager->getRepository(User::class);
    $permRoleRepo = $this->entityManager->getRepository(PermRole::class);
    $permissionRepo = $this->entityManager->getRepository(Permission::class);
    $user = $userRepo->findOneBy(['uuid' => $userUuid]);
    $permission = $permissionRepo->findOneBy(['uuid' => $permissionUuid]);        
    foreach ($user->getPermrole() as $userRole) {
        var_dump($userRole);
        $role = $permRoleRepo->findOneBy(['uuid' => $userRole->getUuid()]);
        var_dump($role);
        $rolePerms = $role->getPermissions();
        if (!is_null($rolePerms)) {
            foreach ($rolePerms as $perm) {
                var_dump($perm->getUuid());
                if ($perm->getUuid() === $permissionUuid) {
                    return true;
                }
            }
        }
    }
    return false;
}