Truthy and Falsy

In Twig, as in many programming languages, values are often evaluated in a boolean context, meaning they are interpreted as either true or false. This concept is essential for controlling the flow of templates through conditionals and loops.

What is Truthy?

In Twig, a value is considered "truthy" if it evaluates to true in a boolean context. These values include:

true
Any non-empty string, such as "hello" or "0"
Any non-zero number, such as 1, -1, or 3.14
Any non-empty array or object

Examples of Truthy Values:

{% if "hello" %}
  This will be displayed.
{% endif %}
{% if 42 %}
  This will also be displayed.
{% endif %}

What is Falsy?

A value is considered "falsy" if it evaluates to false in a boolean context. These values include:

false
null
An empty string ""
The number 0 (zero)
An empty array [] or empty object

Examples of Falsy Values:

{% if "" %}
  This will NOT be displayed.
{% endif %}
{% if 0 %}
  This will NOT be displayed either.
{% endif %}

Using Truthy and Falsy in Conditionals

Understanding truthy and falsy values is particularly important when using in Twig templates. This allows you to perform actions based on whether a value exists, whether it's empty, or if it meets certain criteria.

{% if global.customer.first_name %}
  Hello, {{ global.customer.first_name }}!
{% else %}
  Hello!
{% endif %}