acf add field to product variation code example

Example: acf woocommerce variations

// Render fields at the bottom of variations - does not account for field group order or placement.
add_action( 'woocommerce_product_after_variable_attributes', function( $loop, $variation_data, $variation ) {
    global $abcdefgh_i; // Custom global variable to monitor index
    $abcdefgh_i = $loop;
    // Add filter to update field name
    add_filter( 'acf/prepare_field', 'acf_prepare_field_update_field_name' );
    
    // Loop through all field groups
    $acf_field_groups = acf_get_field_groups();
    foreach( $acf_field_groups as $acf_field_group ) {
        foreach( $acf_field_group['location'] as $group_locations ) {
            foreach( $group_locations as $rule ) {
                // See if field Group has at least one post_type = Variations rule - does not validate other rules
                if( $rule['param'] == 'post_type' && $rule['operator'] == '==' && $rule['value'] == 'product_variation' ) {
                    // Render field Group
                    acf_render_fields( $variation->ID, acf_get_fields( $acf_field_group ) );
                    break 2;
                }
            }
        }
    }
    
    // Remove filter
    remove_filter( 'acf/prepare_field', 'acf_prepare_field_update_field_name' );
}, 10, 3 );

// Filter function to update field names
function  acf_prepare_field_update_field_name( $field ) {
    global $abcdefgh_i;
    $field['name'] = preg_replace( '/^acf\[/', "acf[$abcdefgh_i][", $field['name'] );
    return $field;
}
    
// Save variation data
add_action( 'woocommerce_save_product_variation', function( $variation_id, $i = -1 ) {
    // Update all fields for the current variation
    if ( ! empty( $_POST['acf'] ) && is_array( $_POST['acf'] ) && array_key_exists( $i, $_POST['acf'] ) && is_array( ( $fields = $_POST['acf'][ $i ] ) ) ) {
        foreach ( $fields as $key => $val ) {
            update_field( $key, $val, $variation_id );
        }
    }
}, 10, 2 );