add_row in ACF Pro isn't saving repeater values - wordpress

Question

My Situation
I'm using Advanced Custom Fields Pro to store metadata for a post in wordpress.
My posts are created dynamically (not through the administrative interface), which means that I explicitly need to populate metadata using field keys, not field names. One of my fields is a repeater field with a single text area and another is a standard text area.
My Code
The following code is what I call (once per post). The post is created using wp_insert_post() earlier.
// Populate "Name"
update_field('field_566e360961c2f', 'John Doe', $wp_identifier);
// Populate "Sponsors"
foreach($sponsors as $sponsor) {
// Define "Sponsor Name"
$new_sponsor = array(
'field_566e32fb943a5' => 'Beats and Corn Companye'
);
add_row('field_566e32bd943a4', $new_sponsor, $wp_identifier);
}
The result of this is that standard text fields populate, and a single "sponsor" repeater item is created, but the value of the sponsor name is blank.
The relevant wp_postmeta data that is generated looks like this:
| 18226 | 71 | name | John Doe
| 19234 | 71 | sponsors | 1 |
| 19235 | 71 | _0_field_566e32fb943a5 | Beats and Corn Company |
My Question
What am I doing wrong? Looking at the documentation for add_row() this appears to be the correct approach. Is it possible that repeater fields have a different way of notating keys that I'm not aware of?

Answer 1

This isn't made incredibly clear in the documentation today, but it turns out add_row only works if an existing row had already been saved. When trying to populate a repeater field for the very first time you have to use update_field instead and pass an array of value arrays.
The corrected code:
// Populate "Name"
update_field('field_566e360961c2f', 'John Doe', $wp_identifier);
// Populate "Sponsors"
$new_sponsors = array();
foreach($sponsors as $sponsor) {
// Define "Sponsor Name"
$new_sponsor = array(
'field_566e32fb943a5' => 'Beats and Corn Companye'
);
$new_sponsors[] = $new_sponsor;
}
update_field('field_566e32bd943a4', $new_sponsors, $wp_identifier);