How to increase meta tag description field to 320 characters?

Question

We are using metatag v8.x-1.5 on our D8 site (v8.5.3). When filling out the metatag description field, we enter any where from 180-320 characters into the field. However, when the page is displayed it is cutting off after 135 characters.

How can we increase the number of characters that are displayed?

Steps to reproduce:

1. Enter "Compellingly re-engineer bleeding-edge interfaces whereas interoperable quality vectors. Uniquely incubate one-to-one action items before best-of-breed catalysts for change. Interactively." into the Metatag Description field.

Current behavior:

<meta name="description" content="Compellingly re-engineer bleeding-edge interfaces whereas interoperable quality vectors">

Expected behavior:

<meta name="description" content="Compellingly re-engineer bleeding-edge interfaces whereas interoperable quality vectors. Uniquely incubate one-to-one action items before best-of-breed catalysts for change. Interactively.">

Answer 1

I had to write a hook_page_attachments_alter for this

function mymodule_page_attachments_alter(array &$page) {
  foreach($page['#attached']['html_head] as &$html_head) {
    if($html_head[1] == 'description') {
      $html_head_content = $html_head[0]['#attributes']['content'];
      if(Unicode::strlen($html_head_content) > 320) {
        $html_head[0]['#attributes']['content'] = Unicode::truncate($html_head_content, 320);
      }
    }
  }
}