Imthiaz Blog

Symfony Doctrine Many to Many Relationship (ManyToMany)

April 24, 2018
Imthiaz
Programming
0 Comments

Many to many relations are one of the mostly used relations in the relational database. It took a while for me to figure how to properly configure this relation in Symfony Doctrine. I am sharing this so it might be useful for someone.

Used very simple example students and course. A student can opt for multiple courses and a single course can be opted by multiple students.

And Entity class should be like this…

namespace AppBundle\Entity;

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

/**
 * Student
 *
 * @ORM\Table(name="ab_student")
 * @ORM\Entity(repositoryClass="AppBundle\Repository\StudentRepository")
 */
class Student
{
    /**
     * @var int
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @var string
     *
     * @ORM\Column(name="name", type="string", length=255)
     */
    private $name;

    /**
     * @var string
     *
     * @ORM\Column(name="email", type="string", length=255)
     */
    private $email;

    /**
     * @var \DateTime
     *
     * @ORM\Column(name="dob", type="datetime")
     */
    private $dob;

    /**
     * @var ArrayCollection
     * @ORM\ManyToMany(targetEntity="AppBundle\Entity\Course", inversedBy="students", fetch="EAGER")
     * @ORM\JoinTable(
     *     name="ab_student_2_course",
     *     joinColumns={@ORM\JoinColumn(name="course_id", referencedColumnName="id", nullable=false, onDelete="cascade")},
     *     inverseJoinColumns={@ORM\JoinColumn(name="student_id", referencedColumnName="id", nullable=false, onDelete="cascade")}
     * )
     */
    private $courses;

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

    /**
     * Get id
     *
     * @return int
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * Set name
     *
     * @param string $name
     *
     * @return Student
     */
    public function setName($name)
    {
        $this->name = $name;

        return $this;
    }

    /**
     * Get name
     *
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     * Set email
     *
     * @param string $email
     *
     * @return Student
     */
    public function setEmail($email)
    {
        $this->email = $email;

        return $this;
    }

    /**
     * Get email
     *
     * @return string
     */
    public function getEmail()
    {
        return $this->email;
    }

    /**
     * Set dob
     *
     * @param \DateTime $dob
     *
     * @return Student
     */
    public function setDob($dob)
    {
        $this->dob = $dob;

        return $this;
    }

    /**
     * Get dob
     *
     * @return \DateTime
     */
    public function getDob()
    {
        return $this->dob;
    }

    /**
     * @return ArrayCollection
     */
    public function getCourses()
    {
        return $this->courses;
    }

    /**
     * @param ArrayCollection $courses
     */
    public function setCourses($courses)
    {
        $this->courses = $courses;
    }

}

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/**

* @var string

*

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

*/

private $email;

/**

* @var \DateTime

*

* @ORM\Column(name="dob", type="datetime")

*/

private $dob;

/**

* @var ArrayCollection

* @ORM\ManyToMany(targetEntity="AppBundle\Entity\Course", inversedBy="students", fetch="EAGER")

* @ORM\JoinTable(

* name="ab_student_2_course",

* joinColumns={@ORM\JoinColumn(name="course_id", referencedColumnName="id", nullable=false, onDelete="cascade")},

* inverseJoinColumns={@ORM\JoinColumn(name="student_id", referencedColumnName="id", nullable=false, onDelete="cascade")}

* )

*/

private $courses;

public function __construct()

namespace AppBundle\Entity;

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

/**
 * Course
 *
 * @ORM\Table(name="ab_course")
 * @ORM\Entity(repositoryClass="AppBundle\Repository\CourseRepository")
 */
class Course
{
    /**
     * @var int
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @var string
     *
     * @ORM\Column(name="name", type="string", length=255)
     */
    private $name;


    /**
     * @var ArrayCollection
     * @ORM\ManyToMany(targetEntity="AppBundle\Entity\Student", mappedBy="courses", cascade={"all"})
     */
    private $students;

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

    /**
     * Get id
     *
     * @return int
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * Set name
     *
     * @param string $name
     *
     * @return Course
     */
    public function setName($name)
    {
        $this->name = $name;

        return $this;
    }

    /**
     * Get name
     *
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     * @return ArrayCollection
     */
    public function getStudents()
    {
        return $this->students;
    }

    /**
     * @param ArrayCollection $students
     */
    public function setStudents($students)
    {
        $this->students = $students;
    }

}

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/**

* @var string

*

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

*/

private $name;

/**

* @var ArrayCollection

* @ORM\ManyToMany(targetEntity="AppBundle\Entity\Student", mappedBy="courses", cascade={"all"})

*/

private $students;

public function __construct()

{

$this->students = new ArrayCollection();

}

The above entities will create the following SQL and it will also create the cross-reference table.

CREATE TABLE ab_student 
  ( 
     id    INT auto_increment NOT NULL, 
     name  VARCHAR(255) NOT NULL, 
     email VARCHAR(255) NOT NULL, 
     dob   DATETIME NOT NULL, 
     PRIMARY KEY(id) 
  ) 
DEFAULT CHARACTER SET utf8 
COLLATE utf8_unicode_ci 
engine = innodb; 

CREATE TABLE ab_student_2_course 
  ( 
     course_id  INT NOT NULL, 
     student_id INT NOT NULL, 
     INDEX idx_87d76467591cc992 (course_id), 
     INDEX idx_87d76467cb944f1a (student_id), 
     PRIMARY KEY(course_id, student_id) 
  ) 
DEFAULT CHARACTER SET utf8 
COLLATE utf8_unicode_ci 
engine = innodb; 

CREATE TABLE ab_course 
  ( 
     id   INT auto_increment NOT NULL, 
     name VARCHAR(255) NOT NULL, 
     PRIMARY KEY(id) 
  ) 
DEFAULT CHARACTER SET utf8 
COLLATE utf8_unicode_ci 
engine = innodb; 

ALTER TABLE ab_student_2_course 
  ADD CONSTRAINT fk_87d76467591cc992 FOREIGN KEY (course_id) REFERENCES 
  ab_student (id) ON DELETE CASCADE; 

ALTER TABLE ab_student_2_course 
  ADD CONSTRAINT fk_87d76467cb944f1a FOREIGN KEY (student_id) REFERENCES 
  ab_course (id) ON DELETE CASCADE;

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COLLATE utf8_unicode_ci

engine = innodb;

CREATE TABLE ab_student_2_course

(

course_id INT NOT NULL,

student_id INT NOT NULL,

INDEX idx_87d76467591cc992 (course_id),

INDEX idx_87d76467cb944f1a (student_id),

PRIMARY KEY(course_id, student_id)

)

DEFAULT CHARACTER SET utf8

COLLATE utf8_unicode_ci

engine = innodb;

CREATE TABLE ab_course

Hope this helps 😉

Thanks @mohammed999_offroader_fj 😘

April 20, 2018
Imthiaz

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Why do we need to upgrade PHP 5.6 to PHP 7.2?

April 8, 2018
Imthiaz
Programming

Rest in peace PHP 5.6

The current version of PHP which is 5.6 has reached the end of life on 19th Jan 2017. PHP team has stopped support for 5.6, and no more new features added.
Security support for 5.6 is up to Jan 2019. On Jan 2019 PHP 5.6 officially dead.
The newer version of Linux and server software has already stopped supporting PHP 5.6 which creates a huge security risk.
Updating old server will be hard as it may break the PHP due to compatibility issues.
All major PHP libraries and frameworks will drop support for PHP 5.6
7.2 end of life is in Jan 2021
7.2 is so much faster than 5.6
7.X has new Zend Engine
Reduction in the memory usage
Consistent 64bit support
Better Error handling
More secure & better handling with SSL and cryptography

Install MySQL 5.6 and phpMyAdmin on Ubuntu 16.04

April 7, 2018
Imthiaz
Linux

To Install MySQL 5.6 and phpMyAdmin on Ubuntu just follow the command one by one bellow.

For phpMyAdmin to work, you need PHP to be installed. To install PHP 5.6 😉

add-apt-repository -y ppa:ondrej/mysql-5.6

apt-get update

apt-get install mysql-server-5.6

mysql_secure_installation

apt-get install phpmyadmin

service apache2 restart

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add-apt-repository -y ppa:ondrej/mysql-5.6

apt-get update

apt-get install mysql-server-5.6

mysql_secure_installation

apt-get install phpmyadmin

service apache2 restart