liquid/_basics/types.md

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Types

Liquid objects can return one of six types:

• string
• number
• boolean
• nil
• array
• EmptyDrop

Liquid variables can be initialized by using the assign or capture tags.

String

Strings are declared by wrapping a variable's value in single or double quotes.

{% highlight liquid %} {% raw %} {% assign my_string = "Hello World!" %} {% endraw %} {% endhighlight %}

Number

Numbers include floats and integers.

{% highlight liquid %} {% raw %} {% assign my_int = 25 %} {% assign my_float = 39.756 %} {% endraw %} {% endhighlight %}

Booleans

Booleans are either true or false. No quotations are necessary when declaring a boolean.

{% highlight liquid %} {% raw %} {% assign foo = true %} {% assign bar = false %} {% endraw %} {% endhighlight %}

Nil

Nil is a special empty value that is returned when Liquid code has no results. It is not a string with the characters "nil".

Nil is treated as false in the conditions of if blocks and other Liquid tags that check the truthfulness of a statement.

In the following example, if the user does not exist (that is, user returns nil), Liquid will not print the greeting:

{% highlight liquid %} {% raw %} {% if user %} Hello {{ user.name }}! {% endif %} {% endraw %} {% endhighlight %}

Tags or outputs that return nil will not print anything to the page.

Input

{% highlight html %}{% raw %} The current user is {{ user.name }} {% endraw %}{% endhighlight %}

Output

{% highlight html %}{% raw %} The current user is {% endraw %}{% endhighlight %}

Arrays

Arrays hold lists of variables of any type.

Accessing items in arrays

To access items in an array, you can loop through each item in the array using a for or tablerow tag.

Input

{% highlight html %}{% raw %} {% for user in site.users %} {{ user }} {% endfor %} {% endraw %}{% endhighlight %}

Output

{% highlight html %}{% raw %} Tobi Lina Tetsuro Adam {% endraw %}{% endhighlight %}

Accessing a specific item in an array

You can use square bracket [ ] notation to access a specific item in an array. Array indexing starts at zero.

Input

{% highlight html %}{% raw %} {{ site.users[0] }} {{ site.users[1] }} {{ site.users[3] }} {% endraw %}{% endhighlight %}

Output

{% highlight html %}{% raw %} Tobi Lina Adam {% endraw %}{% endhighlight %}

Initializing an array

It is not possible to initialize an array using only Liquid.

You can, howver, use the split filter to break a single string into an array of substrings.

EmptyDrop

An EmptyDrop object is returned whenever you try to access a non-existent object (for example, a collection, page or blog that was deleted or hidden) by handle. In the example below, page_1, page_2 and page_3 are all EmptyDrop objects.

{% highlight html %}{% raw %} {% assign variable = "hello" %} {% assign page_1 = pages[variable] %} {% assign page_2 = pages["i-do-not-exist-in-your-store"] %} {% assign page_3 = pages.this-handle-does-not-belong-to-any-page %} {% endraw %}{% endhighlight %}

EmptyDrop objects only have one attribute, empty?, which is always true.

Collections and pages that do exist do not have an empty? attribute. Their empty? is “falsy”, which means that calling it inside an if statement will return false. When using an unless statement on existing collections and pages, empty? will return true.

Applications in themes

Using the empty? attribute, you can check to see if a page exists or not before accessing any of its other attributes.

{% highlight html %}{% raw %} {% unless pages.frontpage.empty? %}

{{ pages.frontpage.title }}

{{ pages.frontpage.content }}

{% endunless %} {% endraw %}{% endhighlight %}

It is important to see if a page exists or not first to avoid outputting empty HTML elements to the page, as follows:

{% highlight html %}{% raw %}

{% endraw %}{% endhighlight %}

You can perform the same verification with collections as well:

{% highlight html %}{% raw %} {% unless collections.frontpage.empty? %} {% for product in collections.frontpage.products %} {% include 'product-grid-item' %} {% else %}

We do have a 'frontpage' collection but it's empty.

{% endfor %} {% endunless %} {% endraw %}{% endhighlight %}