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Question

Consider {{ item.nw is defined and item.nw ? ' target="_blank"' }} in the below script. Is there a more concise way to do this?

I thought {{ item.nw ?? ' target="_blank"' }} might work but it returns item.nw if item.nw is not false and target="_blank"' if item.nw is false (reference https://twig.symfony.com/doc/2.x/templates.html#test-operator)

{% macro menu(menu,active) %}
{# menu is an associated array of containing:
name.  required
path or id: One of the two are required.  If both, URL will use path
path.  optional and defaults to javascript:void(0)
id.  optional and defaults to not adding an id to the item.
nw.  optional and defalts to false.  This is a flag for a new window.
class.  optional and defaults to not adding an class to the item.
#}
{% for item in menu %}
{% set path = item.path is defined?item.path:"javascript:void(0)" %}
{% set id = item.id is defined?item.id:null %}
{% set class = item.class is defined?item.class:"" %}
{% if (path == active or id == active) %}
{% set class = class~' active ' %}
{% endif%}
{% if loop.first %}
{% set class = class~' first ' %}
{% elseif loop.last %}
{% set class = class~' last ' %}
{% endif %}
<li class="{{ class|trim }}">
    <a href="{{ path }}"{{ item.nw is defined and item.nw ? ' target="_blank"' }}{{ id?"id=#{id}" }}>{{item.name}}</a>
</li>
{% endfor %}
{% endmacro %}

Answer 1

Null coalesce will only return the value on the left if "it is defined and not null". Remember that false is a value also.

{{ item.nw ?? ' target="_blank"' }}

When "Strict Mode" is turned on you should check every variable you use in the Twig Template. It might be verbose, but it's better than having your template break.

There are alternative ways to check variables if you use the default filter. https://twig.symfony.com/doc/2.x/filters/default.html

{{ item.nw|default() is not false ? ' target="_blank"' }}

{{ item.nw|default() == 'some_value' ? ' target="_blank"' }}