Check if a variable is a date with Twig

Question

I have an array of variables that I want to display in a Twig template and each variable can be either a string or a date.

If the variable is a date, I want to apply

Answer 1

Michael's solution works in most cases, but there are some special cases you should consider when you want to have a universal solution.

First, an object that you test for having a getTimestamp() method doesn't have to be a DateTime instance. I can thing of many cases when the timestamp field would be useful in an object, so I would test the getTimezone() method instead.

Second, if my_var is an object having a magic __call method defined, then all such tests would turn out positive. That's why I suggest the following negative test:

{% if my_var.timezone is defined and my_var.nonExistingProperty is not defined %}
    {{ my_var|date('m/d/Y') }}
{% else %}
    {{ my_var }}
{% endif %}

The second case was the one I recently struggled with because of using Propel ORM objects. The base class has the __call method that catches all Twig is defined tests.