[Resolved] Update types custom field in parent post from custom field in child post

[Author]

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[culturaI]

Hello i have:
parent post type: "contatto"
child post type "corso"
custom field "data-inizio corso" in child "corso"
custom field "data-ultimo-corso" in parent "contatto"

I would like that when filled "data-inizio-corso" the value is copied in "data-ultimo-corso" updating or creating the post.

I followed this thread succefully:
https://toolset.com/forums/topic/calculate-value-of-a-custom-field-based-on-other-custom-fields-values/

and tried with this guide without success:
https://toolset.com/documentation/user-guides/many-to-many-post-relationship/

My code:

function inserisce_data_ultimo_corso( $post_ID ) {      
    if ( get_post_type( $post_ID ) == 'corso' ) {
		        $data_corso_inserito       = get_post_meta($post_ID, 'wpcf-data-inizio-corso', true);
		        update_post_meta( $post_ID, 'wpcf-data-ultimo-corso-test', $data_corso_inserito );
	}
}
		add_action( 'save_post', 'inserisce_data_ultimo_corso', 99 );

It allow me to update custom field "data-ultimo-corso-test" if it's in the same post, i didn't understand how to update the parent post.

I know that line
[php]
update_post_meta( $post_ID, 'wpcf-data-ultimo-corso-test', $data_corso_inserito );
[php]
has to be changed and i think i have to to use "wpcf_belongs", but i can't understand how.

Thanks, Luigi

[Luo Yang]

Dear CulturaI,

Types plugin is using a custom field "_wpcf_belongs_[parent-slug]_id" to store the parent post ID, for example, if the parent post type is using slug "contatto", then in single child "corso" post, there is a hidden field "_wpcf_belongs_contatto_id", the filed value is parent post ID, so if "$post_ID" is a child "corso" post ID, you can get the parent "contatto" post ID with PHP codes:

$contatto_id = get_post_meta($post_ID, '_wpcf_belongs_contatto_id', true);

Then use the $contatto_id to update the custom field "data-ultimo-corso" to what you want.

[culturaI]

Thanks Luo it's working good! Works in CRED too.

My code for reference

function inserisce_data_inizio_ultimo_corso( $post_ID ) {      
    if ( get_post_type( $post_ID ) == 'corso' ) {
		        $data_inizio_corso_inserito       = get_post_meta($post_ID, 'wpcf-data-inizio-corso', true);
		        $contatto_id = get_post_meta($post_ID, '_wpcf_belongs_contatto_id', true);
		        update_post_meta( $contatto_id, 'wpcf-data-inizio-ultimo-corso', $data_inizio_corso_inserito );
	}
}
		add_action( 'save_post', 'inserisce_data_inizio_ultimo_corso', 99 );

[Luo Yang]

You are welcome, and thanks for share the codes.