Call to a member function persist() on null - php

Question

Try and data to database and get an error.:
Uncaught Error: Call to a member function persist() on null in
public function addNewPostAction()
{
// Create new Post entity..
// $entityManager = $container->get('doctrine.entitymanager.orm_default');
$post = new Post();
$post->setTitle('Top 10+ Books about Zend Framework 3');
$post->setContent('Post body goes here');
$post->setStatus(Post::STATUS_PUBLISHED);
$currentDate = date('Y-m-d H:i:s');
$post->setDateCreated($currentDate);
$this->entityManager->persist($post);
$this->entityManager->flush();
}
UPDATE:
Error:
Zend\Mvc\Controller\PluginManager::get was unable to fetch or create an instance for get
public function addNewPostAction()
{
// Create new Post entity..
// $entityManager = $container->get('doctrine.entitymanager.orm_default');
$post = new Post();
$post->setTitle('Top 10+ Books about Zend Framework 3');
$post->setContent('Post body goes here');
$post->setStatus(Post::STATUS_PUBLISHED);
$currentDate = date('Y-m-d H:i:s');
$dm = $this->get('doctrine.odm.mongodb.document_manager');
$dm->persist($post);
$dm->flush();
}

Answer 1

From the 2 samples above, it is obvious you are trying to get doctrine `s entity manager.
1st sample:
$this->entityManager
probably the property $entityManager of the controller is not set, also from the commented code
$entityManager = $container->get('doctrine.entitymanager.orm_default');
it is obvious you are trying to get entity manager.
2nd sample:
$this->get('doctrine.odm.mongodb.document_manager');
I assume this is from a symfony example.
Anyway to get the doctrine manager in your controller, you have to inject it, change your controller constructor to accept it as an argument:
class IndexController extends AbstractActionController
{
private $doctrineManager;
public function __construct($doctrineManager)
{
$this->doctrineManager = $doctrineManager;
}
and then inject the doctrine manager to your controller factory in your module.config.php:
'controllers' => [
'factories' => [
Controller\IndexController::class => function ($container) {
return new Controller\IndexController(
$container->get('doctrine.odm.mongodb.document_manager')
);
},
// ...
],
],
Side note: the error "Zend\Mvc\Controller\PluginManager::get was unable to fetch or create an instance for get" is thrown because zend tries any undefined methods to resolve them to a plugin, eg. if you define a plugin with name myAwesomePlugin, you can access it in your action as:
$this->myAwesomePlugin();