Variables
The absolute simplest part of the module puzzle is the variable file. It allows you to quickly and easily render a value from PHP into a Twig template. The implementation can be as complex as you need or want it to be, but ultimately it’s just a very simple tool for outputting a value to Twig.
Before you dive too deep, it’s worth noting that many variable methods (especially the more complex ones) are simply wrappers for a related service method…
public function myFunction($myVariable)
{
return BusinessLogic::$instance->myServices->myFunction($myVariable);
}
You certainly don’t need to refer to a service method. If you want, all of your processing can be done within the variable method itself. But if you intend to write complex logic, or interact with records in a meaningful way, it’s highly recommended that you offload that logic to a services method.
Basic example
In its simplest form, a variable method can simply return a static value.
public function helloWorld()
{
return "Hello World";
}
{# Outputs "Hello World" #}
{{ craft.businessLogic.helloWorld }}
Intermediate example
More often, you’ll use the variable to perform a simple task in PHP. Think of it like a Twig macro, but with all of the capabilities of PHP at your fingertips.
public function add($a, $b)
{
return $a + $b;
}
{# Outputs "7" #}
{{ craft.businessLogic.add(3, 4) }}
You can also set the returned value, and use it for more complicated purposes…
{% set firstNumber = craft.businessLogic.add(3, 4) %}
{% set secondNumber = craft.businessLogic.add(5, 6) %}
{# Adds 7 + 11, outputs "18" #}
{{ firstNumber + secondNumber }}
Expert example
It’s worth mentioning that a variable method can return any type. The examples above show how to get a string or number, but you could also use variables to get an array or object!
public function authorEntries($userId)
{
$entries = \craft\elements\Entry::find()
->authorId($userId)
->all();
}
{# Get an array of entries written by the current user #}
{% set entries = craft.businessLogic.authorEntries(currentUser.id) %}
How you use the variable is completely up to you. Remember, if the logic gets too complex, offload it to a service method!