Symfony 2 Bizarre behavior in the controller - symfony

Question

Symfony 2.3
I have two fields on the form with dates: the date_from and date_to.
The controller after submit performs its own validation. After automatic validatin is OK make my own validation of dates. Before adding the code below the form and submit displays after validation:
date_from 2015-10-01 and date_to 2015-10-02
and after adding the code form displays before submit:
date_from 2015-10-01 and date_to 2015-10-02
after submit:
date_from 2015-10-02 and date_to 2015-10-01
Dates are switched. So it writes to the database.
$date_from = $entity->getDatefrom();
$date_to = $entity->getDateto();
$workdays = 0;
for ( $i = $date_from; $i <= $date_to; $i->setTimestamp(strtotime($i->format('Y-m-d') . " +1 day") ) )
{
if ( !in_array($i, $freedays))
{
if ( date('N', strtotime($i->format('Y-m-d') ) ) < 6 )
{
$workdays++ ;
}
}
}
When i remove this code dates are not switched. But ofcourse i don't have count of working days.

Answer 1

You need to dereference the DateTime Object $date_from using clone before assigning it to $i.
http://php.net/manual/en/language.oop5.references.php
$date_from = $entity->getDatefrom();
$date_to = $entity->getDateto();
$workdays = 0;
for ( $i = clone $date_from; $i <= $date_to; $i->setTimestamp(strtotime($i->format('Y-m-d') . " +1 day") ) )
{
if ( !in_array($i, $freedays))
{
if ( date('N', strtotime($i->format('Y-m-d') ) ) < 6 )
{
$workdays++ ;
}
}
}
PHP doesn't copy objects when assigning them to a new variable it just creates a reference.
$i = $date_from
In this for loop it updates the $i for each iteration
$i->setTimestamp(strtotime($i->format('Y-m-d') . " +1 day") )
Because it's only a reference its this same as
$date_from->setTimestamp(strtotime($i->format('Y-m-d') . " +1 day") )
// OR even
$entity->getDatefrom()->setTimestamp(strtotime($i->format('Y-m-d') . " +1 day") )
Using clone make a copy of the original so $i->setTimestamp(...) won't actually apply to $date_from