CALCUL WITH CONSTRUCTOR IN ENTITY SYMFONY

Question

i need to do a calcul in an entity with symfony (sonata) like: i have 3 labels in my entity with doctrine and i need to save in database a result of: $calcul = $ a + $b;

here is my entity

class National
{
    /**
     * @var int
     */
    private $id;

    /**
     * @var string(unique=true)
     */
    private $selection;
    
    /**
     * @var int
     */
    private $a;
    
    /**
     * @var int
     */
    private $b;
    
    /**
     * @var string
     */
    private $total;

and this is my classic setter and getter

/**
     * Set a
     *
     * @param string $a
     *
     * @return Events
     */
    public function setA($a)
    {
        $this->a = $a;

        return $this;
    }

    /**
     * Get a
     *
     * @return string
     */
    public function getA()
    {
        return $this->a;
    }
    
/**
     * Set b
     *
     * @param string $b
     * @return Events
     */
    public function setB($b)
    {
        $this->b = $b;

        return $this;
    }

so the question is how to do the constructor ???

to have the result in $calcul save in the database

(ex: if i write 5 in label $a et 5 in label $b - i need to have 10 write directly in the label $calcul....)

Answer 1

Recommandation

I do not recommend to do such a thing as persisting calculated data to a database ( 3FN Explanation ).

In a general way you don't want to store a fields which is a result from two or more other fields, as if you need to update one of the original fields, this will also require you to re-calculated a re-store the result at each time, requiring a few more operations each time.

Also, if fore some reason the calcul must change, you'll have to update all of the data which was done with a former calcul. This will become very hard to manage.

If you need to retrieve the results of two or more fields, this should be perform by calling a function where you need it.

Technicaly

Of course, if you still want to do that, or really need it, the way to do it would be:

class National {
   ... // Your fields, getters and setters
   public function calculTotal() {
      $this->total = $this->a + $this->b;
      return $this;
   }
}

In your controller or service

// Fetch you National entity from repository
// Perform the calcul
$national->calculTotal()
// Persist the national entity with the new 'total' fields added to it
$this->entityManager->perist($national);
$this->entityManager->flush();