How to set value for multivalue field in drupal 8 programmatically

Question

I was saving poll choices Programmatically in Drupal 8. I have used Drupal8 Poll choices module.

$node_poll = Poll::load($pollid);
//print_r($node_poll);exit;
$i = array(13,14,15);
foreach($i as $key => $value){
  $node_poll->choice->setValue(
        [
            ['target_id' => $value]
        ]
  );
// But I want to save multiple target ids. now this is saving 15 all the time.

}
$node_poll->question->setValue([
  'value' => 'test',
]);
$node_poll->save();

The following snippet is working fine.

$node_poll->choice->setValue(
        [
            ['target_id' => 13]
       ],
       [
            ['target_id' => 14]
       ],
        [
            ['target_id' => 15]
       ]
    );

How can I, make target ids to be saved dynamically?

Answer 1

I would rewrite your code like this.
N.B.: This an edited version of the original answer, following some helpful points coming from the comments.

$poll = Poll::load($pollid);

$poll->question->setValue(['value' => 'test']);

$target_ids = array(13,14,15);
foreach($target_ids as $target_id){
  $poll->choice->appendItem($target_id);
}
$poll->save();

Hope this does it!

Answer 2

You can work with multi value fields like an array. The field interface will translate this to store it in the database. To simplify it even more:

$target_ids = array(13,14,15);
$node_poll = Poll::load($pollid);
foreach($target_ids as $target_id) {
  $node_poll->choice[] = $target_id;
}
$node_poll->question->value = 'test';
$node_poll->save();

This will add the id's to the field, not overwrite the existing ones. If you want to do this, you can set an empty array at the beginning.