By star-szr on
Change record status: 
Published (View all published change records)
Project: 
Drupal core
Introduced in branch: 
8.0.x
Issue links: 
https://www.drupal.org/node/2447049
Description: 

In Twig templates, render arrays are automatically rendered when printed. But there are use cases for rendering and then passing a render array on to other Twig filters.

A render filter has been added so that render arrays can be rendered by passing them to the filter.

Examples of how to meet this use case before:

{# Example method 1: Set block. #}
{% set foo %}
  {{ content.body }}
{% endset %}

{{ foo|length }}

{# Example method 2: Using the render_var Twig function. #}
{{ render_var(content.body)|length }}

Example after:

{{ content.body|render|length }}
Impacts: 
Themers