Calculate Database Field Value and Send to Views as New Field

Question

I have a database field which stores a timestamp. This timestamp is sent to a custom views provider via hook_views_data(). This timestamp field is created as a date field to utilize the date format options from views.

$data['module']['timestamp'] = [
  'title' => t('Timestamp'),
  'help' => t('Timestamp from module'),
  'field' => [
    'id' => 'date',
  ],
  'sort' => [
    'id' => 'date',
  ],
  'filter' => [
    'id' => 'date',
  ],
];

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In another views field (but with the same DB field), I would like to get the raw field value and run it through something like:

if (field_value > (time() - 800))

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This is a custom module and would prefer not to have any more dependencies. Can this be achieved with hook_views_data() or hook_views_pre_render() or such?

I know there is a contributed module https://www.drupal.org/project/computed_field, but again hoping there is a way in those hooks, or in the view...

The DB table is created with hook_install() and the desired timestamp field output after check would be markup. Happy if it is just sent as markup to the views field.

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I've figured how to access the field values with hook_views_pre_render() as such:

function hook_views_pre_render(&$view) {
  $result = $view->result;
  foreach ($result as $key => $row) {
    kpr($result[$key]->field_name);
    if ($result[$key]->timestamp > (time() - 800)) {
      // Can I do anything here?
    }
    else {
      //
    }
  }
}

Unfortunately, that is not the most important piece of the puzzle. And it is not possible to just add $data['module']['key'] to my hook_views_data() as this requires the unique DB field to exist.

In my use case, I'd be happy if I could rewrite the original timestamp field and append this markup to it.

Answer 1

Take a look at this, it shows how you can create custom fields that you can use within views https://www.webomelette.com/creating-custom-views-field-drupal-8

I've followed this recently and seems to work well