what is the correct way to programmatically set checkboxes (MultiOptionsFieldData) in a migration? (solved)

Question

I need to update existing entries after the creation of a checkbox fields, to apply the default value to everything that was created before the availability of the new field. The code should run in a migration to be deployed along the changes in the project config.

What is the correct way to programmatically set checkboxes (craft\fields\data\MultiOptionsFieldData)?

I verified the migration updates the entry (the title for instance), but not the custom field:

$entries = \craft\elements\Entry::find()
  ->section('sectionProduct')
  ->all();

foreach($entries as $entry) {
  $options = $entry->distribution->getOptions();
  foreach($options as $opt) {
    $opt->selected = true;
  }
  $entry->distribution->setOptions($options);
  Craft::$app->getElements()->saveElement($entry);
}

After running the migration, the control panel never shows the checkboxes flagged (the checkbox field has two possible values).

TIA

Answer 1

Sleeping on it (and peeking at the db) provided a solution, with even simpler code:

$entries = \craft\elements\Entry::find()
  ->section('sectionProduct')
  ->all();

foreach($entries as $entry) {
  $entry->setFieldValue('distribution', ["1", "2"]);
  Craft::$app->getElements()->saveElement($entry);
}

where "1" and "2" are the values associated to the checkboxes.

If you know the checkbox values, use setFieldValue and pass them as an array:

• [] (empty) no checkboxes selected
• ["single value"]
• ["multi", "values"]