How can I retrieve data from ArrayCollection (Symfony)?

Question

animals:

| id | name |
|----|------|
| 1  | cat  |
| 2  | dog  |
| 3  | frog |

category:

| id | name   |
|----|--------|
| 1  | green  |
| 2  | blue   |
| 3  | orange |

animals_category:

| animals_id | category_id |
|------------|-------------|
| 1          | 1           |
| 2          | 1           |
| 2          | 2           |

What I want to do is get the categories for dog:

green, blue

This is my approach:

Controller:

$id = '2';

$result = $this->getDoctrine()->getRepository('Animals:Category')->findByIdJoinedToCategory(['id'=>$id]);

Animals Repository:

   public function findByIdJoinedToCategory()
    {
        $query = $this->getEntityManager()
            ->createQuery(
                'SELECT a, b FROM Animals:Category a
                JOIN a.category b');
        try {
            return $query->getResult();
        } catch (\Doctrine\ORM\NoResultException $e) {
            return null;
        }
    }

But I get an error message:

Unknown Entity namespace alias 'Animals'.

entity Animals:

<?php

namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;

/**
* @ORM\Entity(repositoryClass="App\Repository\AnimalsRepository")
*/
class Animals
{
  /**
  * @ORM\Id()
  * @ORM\GeneratedValue()
  * @ORM\Column(type="integer")
  */
  private $id;


  /**
  * @ORM\Column(type="string", length=255)
  */

  private $name;


  /**
  * @ORM\ManyToMany(targetEntity="Category")
  * @ORM\JoinColumn(name="category", referencedColumnName="id")
  */
  private $category;




  public function getId(): ?int
  {
    return $this->id;
  }


  public function getName()
  {
    return $this->name;
  }

  public function setName($name)
  {
    $this->name = $name;
  }


  public function getCategory()
  {
    return $this->category;
  }

  public function setCategory($category): self
  {
    $this->category = $category;

    return $this;
  }

  public function addCategory(Category $category): self
  {
    $this->category[] = $category;

    return $this;
  }

  public function __construct()
  {
    $this->category = new ArrayCollection();
  }
}

You have to be placed in Animals repository to get them or do a join.. — hoover_D
– hoover_D, Commented Jan 7, 2019 at 9:55
@hoover_D Yes, sorry, I did a mistake in my question. Now it is correct — peace_love
– peace_love, Commented Jan 7, 2019 at 9:59

Jakub Matczak · Accepted Answer · 2019-01-07 10:37:29Z

2

There's no Animals:Category entity. You have entities Animals and Category.

The correct answer depends if you're using Symfony 3 or 4, because Symfony 3 uses entity aliases (namespacing with : notation which you're trying ot use), while Symfony 4 prefers full qualified namespace (\App\Entity\Animals).

So, first mistake is in line where you're trying to get repository:

getRepository('Animals:Category')

And the second in findByIdJoinedToCategory() in DQL query :

'SELECT a, b FROM Animals:Category a
JOIN a.category b'

Now solutions:

Symfony 3

Since it looks you don't have any bundles (I guess it's Symfony 4 but whatever), you don't have any entity namespace alias, so you should simply use its name.

getRepository('Animals')

Now, I assume, that with a you want to reference Animals entity/table, so it should be

'SELECT a, b FROM Animals a
JOIN a.category b'

Symfony 4

If you use Symfony 4, then use should use entity FQNS as entity name (App\Entity\Animals).

So it would be

getRepository('\App\Entity\Animals')

or

getRepository(\App\Entity\Animals::class)

to get repository. The second one is better, because it will be easier to refactor when needed (IDE will be able to find usage of class).

And in query it would be

'SELECT a, b FROM App\Entity\Animals a
JOIN a.category b'

or if you would like to avoid using hardcoded string class names:

'SELECT a, b FROM ' . \App\Entity\Animals:class . ' a
JOIN a.category b'

answered Jan 7, 2019 at 10:37

Jakub Matczak

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5 Comments

peace_love Over a year ago

Thank you for the very good and detailed answer. I will test it out immediately. I have Symfony 4. So just one question. In my controller, I write then: $result = $this->getDoctrine()->getRepository(Animals::class)->findByIdJoinedToCategory(['id'=>$id]);?

Jakub Matczak Over a year ago

Actually I've just noticed, that you have also another issue. Method findByIdJoinedToCategory() method does not take any argument. So you will have to improve that too. It should expect $id parameter, then you should use it inside method to do what you want.

peace_love Over a year ago

If I test your code and dump result then I get an array with all animals cat, dog, frog

Jakub Matczak Over a year ago

That's because, as I wrote in previous comment, you don't really utilize $id parameter to filter the query.

hoover_D Over a year ago

yes, Jarla, check my answer bellow with your id parameter and check if it works please

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