domsson domsson - 3 years ago 353
Twig Question

"Illegal offset type in isset or empty" when using a Twig macro

Using Grav v1.3.8 (running on PHP 5.6.30), I'm currently getting a Server error ("Illegal offset type in isset or empty") when trying to render a Twig template that is using a macro.

What's interesting is that this only happens when I use the macro by itself. As soon as I append a filter, like

, everything works as expected.

The (shortened) macro file,

{% macro ascii(str) %}
{% spaceless %}
{{ str|replace({
'Á': 'A',
'À': 'A',
'Â': 'A',
'Ã': 'A',
'ƒ': 'f'
{% endspaceless %}
{% endmacro ascii %}

The template (MCVE):

{% import 'macros/helpers.twig' as helpers %}

{% set img = helpers.ascii('günter-berger.jpg') %}
{% if[img] is defined %}
<img src="{{[img].url }}">
{% endif %}

This will produce the error. I narrowed it down to the
line. Apparently, the macro is working fine, but the condition will throw an error if fed the output of it, unfiltered. Adding any filter, like
, will get it to work again.

In other words, these work:

  • {% if['günter-berger.jpg'] is defined %}

  • {% if[helpers.ascii('günter-berger.jpg')|trim] is defined %}

But this will throw an error:

  • {% if[helpers.ascii('günter-berger.jpg')] is defined %}

However, trying the same thing on twigfiddle, all three seem to work there.

Maybe an issue with Grav? Can someone point out any possible causes?

Answer Source

I forgot this, but a macro does not return a string but instead returns an instance of a Twig_Markup

{% set test = macro.ascii('Ghünter.jpg') %}
{{ dump(test) }}

Output : object(Twig_Markup)#10679 (2) { ["content":protected]=> string(11) "Ghunter.jpg" ["charset":protected]=> string(5) "UTF-8" }

Because the return type is an object you get this notification as you can't use objects as index. By using a filter on this instance, the magic method __toString method will be called, causing it to return a string, thus making it useable as index for an array

The only was to bypass this, would be writing a filter instead of a macro

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