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, or3.14 - 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:
falsenull- 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 %}
In this example, if global.customer.first_name is an empty string (falsy), the template will output "Hello!".
