How to Access Dynamic Twig Variables and Handle Missing Values?

Accessing Dynamic Twig Variables

Twig offers various ways to access dynamic variable names, providing flexibility in accessing data within templates.

One method involves using an array of objects and looping through them. However, you may encounter challenges when attempting to display placeholders with invoice ID numbers using {{ placeholder1 }}.

Solution through Context Array Access

Instead of employing the attribute function, you can access values in the _context array using bracket notation:

{{ _context['placeholder' ~ id] }}

This syntax enables concise and clear access to variables.

Default Value Handling

To handle variables that may not exist when strict_variables is set to true, consider using the default filter with _context:

{{ _context['placeholder' ~ id]|default }}

{{ attribute(_context, 'placeholder' ~ id)|default }}

This ensures you won't encounter runtime errors due to missing variables.

Variable Existence Verification

To verify if a variable exists, utilize the defined test:

{% if _context['placeholder' ~ id] is defined %} ... {% endif %}

Custom Default Values

To provide custom default values when variables are missing, add an argument to the default filter:

{{ _context['placeholder' ~ id]|default(null) }}

{{ attribute(_context, 'placeholder' ~ id)|default('Default value') }}

Setting strict_variables to true is recommended to prevent accidental errors caused by typos or missing variables.

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