Avoid notice of variable's not being set within dev mode

Question

With dev mode on, I'm getting a warning there is no entry.title, which I know about already because that's what I'm testing for:

{% if entry.title | length == 0 %}
    {% set entry = craft.entries.section('sectionname').slug(craft.request.segment(2)).first() %}
{% endif %}

Is there a way to test for a variable without dev mode triggering this notice?

Answer 1

I've had luck using "is defined" before using other logic operators.

This should do it:

{% if entry.title is defined and entry.title | length == 0 %}
    {% set entry = craft.entries.section('sectionname').slug(craft.request.segment(2)).first() %}
{% endif %}

Answer 2

If you want to set entry to a new value if entry.title is undefined or 0 length, try this:

{% if !(entry is defined and entry.title is defined and entry.title|length) %}
    {% set entry = craft.entries.section('sectionname').slug(craft.request.segment(2)).first() %}
{% endif %}

Answer 3

Since Craft 2.6 you can do this cleanly with the ?? null-coalescing operator:

{% if not (entry.title ?? false) %}
  ...