Migrating from ACF Relationship Fields

If you store relationships in Advanced Custom Fields relationship fields, you can move them into Native Content Relationships.

Approach

1. Export ACF data — ACF stores relationship post IDs in post meta (e.g. my_relation as a serialized array or multiple my_relation_0, my_relation_1 keys). Use WP-CLI, a custom script, or ACF’s export to get post ID → related post IDs.
2. Choose a relation type — Register or use an existing type (e.g. related_to) in NCR. See Custom types.
3. Import — For each post with ACF relations, call ncr_add_relation( $post_id, 'post', $related_id, 'post', 'related_to' ) for each related post.
4. Switch code — Replace ACF get_field( 'my_relation', $post_id ) with ncr_get_related( $post_id, 'post', 'related_to' ) and WP_Query where needed.
5. Optional — Remove or repurpose the ACF field after verification.

Copy-paste migration script

Assume ACF stores related post IDs in meta key my_relation (array of IDs, or ACF’s serialized format). Run once (e.g. via WP-CLI: wp eval-file migrate-acf-to-ncr.php or from a one-off admin page).

<?php
// migrate-acf-to-ncr.php — run once. Replace meta key and type as needed.
if ( ! function_exists( 'ncr_add_relation' ) ) {
	return;
}
$acf_meta_key = 'my_relation';   // Your ACF relationship field name
$ncr_type     = 'related_to';    // NCR relation type

$posts = get_posts( [
	'post_type'      => 'post',
	'post_status'    => 'any',
	'posts_per_page' => -1,
	'fields'         => 'ids',
	'meta_query'     => [ [ 'key' => $acf_meta_key, 'compare' => 'EXISTS' ] ],
] );

foreach ( $posts as $post_id ) {
	$related = get_post_meta( $post_id, $acf_meta_key, true );
	if ( ! is_array( $related ) ) {
		$related = array_filter( (array) $related );
	}
	foreach ( $related as $related_id ) {
		$related_id = (int) $related_id;
		if ( $related_id && get_post_status( $related_id ) ) {
			ncr_add_relation( $post_id, 'post', $related_id, 'post', $ncr_type );
		}
	}
}

Before (ACF): $related = get_field( 'my_relation', $post_id );
After (NCR): $related = ncr_get_related( $post_id, 'post', 'related_to' );

Notes

• ACF relationship fields are one-way (post → posts). NCR supports direction; use direction => 'outgoing' when querying.
• Run a small batch first and compare counts; then run full migration and wp content-relations check to validate.