Compile Error: Cannot use isset() on the result of an expression

Question

I\'m getting this error in a app I am migrating from SF2.0.x to SF2.7:

[1] Symfony\\Component\\Debug\\Exception\\FatalErrorException: Compile Error: Cannot u         


        

Answer 1

Why are you doing so much useless code?

Why don't just:

{% if form_action|empty == true %} {% set form_action = '' %} {% endif %}

Answer 2

From documentation:

isset() only works with variables as passing anything else will result in a parse error.

You're not directly passing a variable to isset(). So you need to calculate the value first, assign it to a variable, and then pass that to isset().

For example, what you're doing at the moment is something like:

if(isset($something === false)) { } // throws a parse error, because $something === false is not a variable

What you need to do instead is:

$something = false;
if(isset($something)) { ... }