Twig null date filter shows current date

Question

According to the documentation

If the value passed to the date filter is null, it will return the current date by default. If an empty string is desired instead of the current date, use a ternary operator:

http://twig.sensiolabs.org/doc/2.x/filters/date.html

The problem is the solution provided entails that we revisit all dates in the application and apply the ternary operation as we never want to show today's date instead of null.

is it possible to override the default date filter? if so how can I implement this. We're using twigs with symfony 2.7

Answer 1

As explained here in the doc, you can override an existing filter:

To overload an already defined filter, test, operator, global variable, or function, re-define it in an extension and register it as late as possible (order matters).

Here is the code to return an empty string instead of the current date if null:

class DateEmptyIfNull extends Twig_Extension
{
    public function getFilters()
    {
        return array(
            new Twig_Filter('date', array($this, 'dateFilter')),
        );
    }

    public function dateFilter($timestamp, $format = 'F j, Y H:i')
    {
        $result = '';
        if($timestamp !== null)
        {
            $result = parent::dateFilter($timestamp, $format);
        }
        return $result;
    }
}

$twig = new Twig_Environment($loader);
$twig->addExtension(new DateEmptyIfNull());