The Liquid Logical Statements are useful if you want to check some variable before displaying it or if you want to create a specific list based on another object.

If Statement

The If Statement allows you to verify the object value when needed:

{% if question.name == "Getting Started" %}
  <p>Only printed if the question name is "Getting Started".</p>
{% endif %}

If you just need to check on a value before printing a default text, you'd need to use the above example. But if you have a default text and want a different one in just a specific case, the best approach is the following one:

{% if question.name == "Getting Started" %}
  <p>Only printed if the question name is "Getting Started".</p>
{% else %}
  <p>This would be the default text, i.e when the question name differs from "Getting Started"</p>
{% endif %}

Notice that the If Statement must be rounded by "{%" and "%}". Also, it needs to be closed properly:

{% if ... %}
  ...
{% endif %}

For Statement

The For Statement allows you to loop through a list of objects. For instance, if you want to loop through the question list from the current category, you can use:

{% for question in category.questions %}
  <h2>{{ question.name }}</h2>
  <a href="{{ question.url }}">{{ question.name }}</a>
{% endfor %}

Another example:

<ul class="top_categories">
  {% for categories in roots_categories %}
    <li class="category_item">
      <a href="{{ category.url }}">{{ category.name }}</a>
    </li>
  {% endfor %}
</ul>

Notice that the For Statement must be rounded by "{%" and "%}". Also, it needs to be closed properly:

{% for ... %}
  ...
{% endfor %}

Real Liquid Example

This example is from a Standard Helpjuice Theme live on our Theme Library:

<ul class="main_navigation">

  {% for category in roots_categories %}
    <li><a href="{{ category.url }}">{{ category.name }}</a></li>

    {% if category.ordered_subcategories.size > 0 %}
      <ul class="subcategories">

        {% for subcategory in category.ordered_subcategories %}
          <li>
            <a href="{{ subcategory.url }}">{{ subcategory.name }}</a>
          </li>
        {% endfor %}

      </ul>
    {% endif %}

{% endfor %}
</ul>

Notice that you can have nested For Statements.

Liquid Filters

You can apply filters on the Liquid Statements. Every time you need to limit a loop statement or change the output of an object value, you can rely on Liquid Filters. Check the Shopify/Liquid Filter Syntax article.‍

Objects List

You can find the complete object reference at Shopify/Liquid Complete Objects Reference‍.

Advanced Shopify/Liquid Syntax

You can find more information about Logical Statements on the official Liquid documentation. The complete Shopify/Liquid documentation is located here.