Models with Doctrine ORM

First we have to install Doctrine ORM:

Let's create two entities

Copy this code into src/Entity/Movie.php

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<?php
namespace App\Entity;

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

/**
 * @ORM\Entity()
 * @ORM\Table(name="movie")
 */
class Movie
{
    /**
     * @ORM\Column(type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @ORM\Column(type="string")
     */
    private $name;

    /**
     * @ORM\Column(type="string", length=100)
     */
    private $director;

    /**
     * @ORM\Column(type="smallint")
     */
    private $year;

    /**
     * @ORM\Column(type="string")
     */
    private $picture;

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

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

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

        return $this;
    }

    public function getDirector()
    {
        return $this->director;
    }

    public function setDirector(string $director)
    {
        $this->director = $director;

        return $this;
    }

    public function getYear()
    {
        return $this->year;
    }

    public function setYear(int $year)
    {
        $this->year = $year;

        return $this;
    }

    public function getPicture()
    {
        return $this->picture;
    }

    public function setPicture(string $picture)
    {
        $this->picture = $picture;

        return $this;
    }

}

Let's update the schema of our database with the mapping of this entity.

First, we need to configure our database. In the file .env we store our configuration parameters. This file should be ignored by Git.

Edit the .env to configure the database:

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DATABASE_URL="mysql://travolta:travolta@127.0.0.1:3306/travolta?charset=utf8mb4&serverVersion=5.7"

Now we should be able to update the schema. Run:

You can inspect the SQL commands that will be applied. To execute them, run:

And the table movie has been created. You can inspect it with PHPMyAdmin or other tools

Relationships

We would like to express the relationship between Movies and Actors. A movie can have many actors and an actor can appear in many movies.

This is a many-to-many relationship.

We can define unidirectional or bidirectional relationships. It is clear that we will want to retrieve the actors of a movie. But would we like to retrieve the movies of an actor? If the answer is yes, then the relationship is bidirectional. If not, it is unidirectional. For this example, we will assume that the relationship is bidirectional.

Bidirectional relationships have an owning side and an inverse side. The rule here is to think which entity is the responsible of the connection management. Are we mentally adding actors to movies or movies to actors?

As our app is about movies, it feels more natural to add actors to movies. If we were building an actor DB it would be the opposite.

Let's define the owning side of the Relationship in src/Entity/Movie.php

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//... Add use directive in the top of the file, with the other use
use Doctrine\Common\Collections\ArrayCollection;

//...

/**
 * @ORM\ManyToMany(targetEntity="Actor", inversedBy="movies")
 */
private $actors;

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

public function getActors()
{
    return $this->actors;
}

public function addActor(Actor $actor)
{
    $actor->addMovie($this);
    $this->actors[] = $actor;

    return $this;
}

public function removeActor(Actor $actor)
{
    $this->actors->removeElement($actor);
    $actor->setMovie(null);

    return $this;
}

Let's define the the inverse side of the Relationship in src/Entity/Actor.php

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//... Add use directive in the top of the file, with the other use
use Doctrine\Common\Collections\ArrayCollection;

//...

/**
 * @ORM\ManyToMany(targetEntity="Movie", mappedBy="actors")
 */
private $movies;

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

public function addMovie(Movie $movie)
{
    $this->movies[] = $movie;
}

public function getMovies()
{
    return $this->movies;
}

public function removeMovie(Movie $movie)
{
    $this->movies->removeElement($movie);
    return $this;
}

After editing the entities, let's update our schema. We first check the SQL that is going to be executed

And then run the actual update: