How can I programmatically render the summary of a textfield?

Question

I can output a textarea field with the following code:

$entity->fieldname->view();

How do I need to change that code for getting the summary of that field?

(Where can I find a documentation of that view-function?)

Answer 1

You have to use the field formatter text_summary_or_trimmed:

$build[] = $entity->fieldname->view([
  'label' => 'hidden',
  'type' => 'text_summary_or_trimmed',
  'settings' => [
    'trim_length' => 600,
  ],
]);

The easiest way to find the field formatter name and settings is configuring a field in a display mode of a content type and exporting the configuration.

How to find the documenation, see How to apply a Field Formatter to a node field programmatically?