Logic

case

Description

When evaluating a large number of conditions.

Syntax

{% case <condition> %}
{% when <value_1> %}
  <code>
...
{% when <value_x> %}
  <code>
{% else %}
  <code>
{% endcase %}

Example

{% case condition %}
{% when 1 %}
  hit 1
{% when 2 %}
  hit 2
{% else %}
  hit else
{% endcase %}

for

Description

Loop over a collection.

Syntax

{% for item in array %}
  {{ item }}
{% endfor %}

Example

Instead of looping over an existing collection, you can define a range of numbers to loop through. The range can be defined by both literal and variable numbers:

# if item.quantity is 4...
{% for i in (1..item.quantity) %}
  {{ i }}
{% endfor %}

1 2 3 4

Variables

During every for loop there are following helper variables available for extra styling needs:

Parameters

Usefulness of a for loop can be enhanced by using parameters, such as reversed limit and offset to manipulate the objects being displayed. Read more

# if item.quantity is 4...
{% for i in (1..item.quantity) reversed limit:2 offset:1 %}
  
{% endfor %}

3 2

if/else/unless

Description

Boolean logic operations are available on all objects.

Syntax

{% if <condition> %}
  <code>
{% else %}
  <code>
{% endif %}

Example

{% if feature.title %}
  {{ feature.title }}
{% endif %}

{% unless feature.body %}
  feature has no content
{% else %}
  {{ feature.body }}
{% endunless %}

Contains

Contains allows you to check if an array contains a specific string. This is very useful when dealing with many_to_many relationships. It will allow you to iterate over related entries, making sure there are no double entries.

Let's say we have a many_to_many relationship between events and performances, meaning that the same performance can belong to multiple events.

So if we want to iterate over all our events to get all performances but we don't want double entries, we could use contains.

{% assign events_slugs = '' %}

{% paginate contents.events by 9 %}
	{% for performance in paginate.collection %}
    {% unless events_slugs contains event._slug %}
      
      {% assign events_slugs = events_slugs | append: event._slug %}
      {{ event.name }}
    
    {% endunless %}
   {% endfor %}
{% endpaginate %}