Cannot redeclare class Cake\ORM\Behavior\ in CakePHP 3 - cakephp-3.0

Question

I created src/Model/Behavior/ModernTreeBehavior.php:
<?php
namespace Cake\ORM\Behavior;
use Cake\Datasource\EntityInterface;
use Cake\Datasource\Exception\RecordNotFoundException;
use Cake\Event\Event;
use Cake\ORM\Behavior;
use Cake\ORM\Entity;
use Cake\ORM\Query;
use InvalidArgumentException;
use RuntimeException;
class ModernTreeBehavior extends Behavior
{
/**
* Cached copy of the first column in a table's primary key.
*
* #var string
*/
protected $_primaryKey;
/**
* Default config
*
* These are merged with user-provided configuration when the behavior is used.
*
* #var array
*/
protected $_defaultConfig = [
'implementedFinders' => [
'children' => 'findChildren',
'treeList' => 'findTreeList'
],
'implementedMethods' => [
'childCount' => 'childCount',
'getLevel' => 'getLevel'
],
'parent' => 'parent_id',
'path' => 'path',
'scope' => null,
'level' => null
];
public function getLevel($entity)
{
$primaryKey = $this->_getPrimaryKey();
$id = $entity;
if ($entity instanceof EntityInterface) {
$id = $entity->get($primaryKey);
}
$config = $this->config();
$entity = $this->_table->find('all')
->select([$config['path']])
->where([$primaryKey => $id])
->first();
if ($entity === null) {
return false;
}
return substr_count($entity[$config['path']], '-') + 1;
}
/**
* Returns a single string value representing the primary key of the attached table
*
* #return string
*/
protected function _getPrimaryKey()
{
if (!$this->_primaryKey) {
$this->_primaryKey = (array)$this->_table->primaryKey();
$this->_primaryKey = $this->_primaryKey[0];
}
return $this->_primaryKey;
}
}
I used $this->addBehavior('ModernTree'); in CommentTables.php
and I got error Fatal error: Cannot redeclare class Cake\ORM\Behavior\ModernTreeBehavior in .../src/Model/Behavior/ModernTreeBehavior.php on line 0
But if I paste /src/Model/Behavior/ModernTreeBehavior.php into built-in file TreeBehavior.php and load TreeBehavior.php, everything so goods.
Can you tell me the reason?

Answer 1

The namespace declaration of your class is wrong, it should be:
namespace App\Model\Behavior;