Variables Overview

Variables are objects that are available for reference by the template. Some variables are reserved for use by Marketpath CMS and are defined by the request or page, while others may be created or modified using template markup. All variables are stored on a scope and are accessible to all markup inside that scope.

A variable can also supply a method’s argument name or its whole argument list, using the reference (&) and variable (*) argument forms described on Methods Overview.

Scope is the context in which a variable is accessible. Scopes may be nested similarly to how partial templates may be nested - with a root scope which may contain child scopes, each of which may also contain child scopes.

Any object on a parent scope is accessible in all child scopes unless the child scope has another object by the same name. Objects on a child scope, however, are no longer accessible on the parent scope once the child scope is complete.

Additionally, if an object exists by the same name on both a parent and a child scope, only the object on the child scope will be accessible until the child scope is complete.

When variable scoping is utilized correctly, it is possible for multiple templates to use the same variable names without affecting each other's behavior. Alternatively, if the template developer needs a template to modify the behavior of another template, they may use the root scope to share information between templates that are not nested.

The root scope is the top-most scope used by the initial page template.

Child scopes are created inside most block methods (eg: {% if %}, {% for %}, {% capture %}, etc...) as well as inside partial templates. The child scope is deleted when the block method is closed (eg: {% endif %}, {% endfor %}, {% endcapture %}, etc...) or the partial template finishes rendering.

The liquid developer documentation should indicate which block methods create child scopes.

While it is possible to create templates without a good understanding of scope, it may be helpful to understand how liquid variables are scoped in order to create truly reusable templates or integrate smoothly with code written by other developers.

By using variable scopes effectively, developers can create and edit intuitive and reusable templates without interfering with functionality implemented by other template developers on the same site. All the developer needs to do is store their objects on the child scope and when their template is done rendering it will not have disturbed any of the parent template objects or variables. For example: you could use the variable "start" even if the same variable is used by a parent template, and when your template is done rendering the "start" object would be unchanged in the parent scope.

There are three different ways to save objects on the scope which are designed to give you full control over where objects are saved without becoming overly complicated:
• var stores the variable on the current scope. Once the current scope is completed, the variable will no longer be accessible. This is the default functionality for everything except for the {% assign %} and {% set %} methods.
• set updates the variable on the closest scope which it is already defined on. If the variable has not been defined on any scope, it will be stored on the root scope.
• assign removes the variable from all scopes and stores it on the root scope.

When writing templates, the best practice is to utilize var and set wherever possible and reserve assign for cases where it is specifically necessary. By restricting your variables to the scopes where they are used, you make your code more friendly and compatible with code written by other developers who may wish to use the same variable names.

Note that there is currently no way to unset a variable from a scope other than using the assign method to define the variable at the root scope. Setting a variable to null does not remove it from the scope.

{{ test1 }}
{%- var test1 = 'out1' -%}
,{{ test1 }}
{%- if true -%}
	,{{ test1 }}
	{%- var test1 = 'out2' -%}
	,{{ test1 }}
{%- endif -%}
,{{ test1 }}

,out1,out1,out2,out1

{%- var test2 = 'out1' -%}
{{ test2 }}
{%- if true -%}
	{%- var test2 = 'out2' -%}
	,{{ test2 }}
	{%- set test2 = 'out3' -%}
	,{{ test2 }}
	{%- if true -%}
		{%- set test2 = 'out4' -%}
		,{{ test2 }}
	{%- endif -%}
	,{{ test2 }}
{%- endif -%}
,{{ test2 }}

out1,out2,out3,out4,out4,out1

{{ test3 }}
{%- if true -%}
	{%- var test3 = 'out1' -%}
	,{{ test3 }}
	{%- if true -%}
		{%- assign test3 = 'out2' -%}
		,{{ test3 }}
	{%- endif -%}
	,{{ test3 }}
{%- endif -%}
,{{ test3 }}

,out1,out2,out2,out2

{%- var title = entity.name | default: 'Untitled' -%}
<p>{{ title }}</p>

{%- var tag = '' -%}
{%- if entity.tags is_list and entity.tags.is_valid -%}
	{%- set tag=entity.tags | first -%}
{%- endif -%}
{%- datastore_items datastore:"products" tag:tag -%}

{%- var tag = tag -%}
{%- if entity.tags is_list and entity.tags.is_valid -%}
	{%- set tag=entity.tags | first -%}
{%- endif -%}
{%- datastore_items datastore:"products" tag:tag -%}

{%- if entity.tags is_list and entity.tags.is_valid -%}
	{%- assign num_tags = entity.tags | size -%}
{%- endif -%}
There are {{num_tags | default:0}} tags on this entity

{%- var minDate = "now" | midnight -%}
{%- var maxDate = "now" | midnight | add_months: 1 -%}
{%- calendar_entries var entries = start_date:minDate end_date:maxDate limit:30 sort_by:"start_date" sort_direction:"asc" -%}

{%- blog_post post = "post" -%}
{{- post | object_type -}}
{{- post | object_type: true }}

blog_post
object