[Resolved] How to get child fields from parent in PHP

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[fabianT]

Dear Support-Team,

I need a JSON with some Post data vom parent 'erinnerungsort' and his childs 'chronikeintrag'. I tried some googleing, but I could not work it out.

I am trying to:

function places_query_posts_callback() {
  $args = array (
    'post_type' => 'erinnerungsort',
    'orderby' => 'post_title',
    'order' => 'ASC',
  );
  $query = new WP_Query( $args );
  $response = array();
  foreach ( $query->posts as $result ) {
    // $geodata_raw = get_post_meta($result->ID, 'wpcf-geodaten', true);
    // $geodata_raw = substr($geodata_raw,1,(strlen($geodata_raw)-2));
    // $geodata = explode(',', $geodata_raw);
    $data = array();
    $data['id'] = $result->ID;
    // $data['lat'] = $geodata[0];
    // $data['lng'] = $geodata[1];
    $data['lat'] = types_render_field("geodaten", array('post_id'   => $result->ID,'format'    => 'FIELD_LATITUDE'));
    $data['lng'] = types_render_field("geodaten", array('post_id'   => $result->ID,'format'    => 'FIELD_LONGITUDE'));
    $data['title'] = $result->post_title;
    $data['tooltip'] = get_post_meta($result->ID, 'wpcf-tooltip');
    $data['content'] = $result->post_content;
    $data['teaser'] = substr($result->post_content, 0, 200);
    $data['type'] = array_shift(get_the_terms($result->ID, 'artdesortes'));
    $data['region'] = array_shift(get_the_terms($result->ID, 'region'));
    $data['thumb'] = get_the_post_thumbnail_url($result->ID);
    //$data['images'] = get_post_meta($result->ID, 'wpcf-bild');
    $data['chronik'] = 'chronik';
    $data['link'] = get_permalink($result->ID) ;

    /* Get childs 'chronikeintrag' from parent 'erinnerungsort' */
    $child_posts = types_child_posts("chronikeintrag");
    foreach ($child_posts as $child_post) {
        $data['chroniktitel'] =  $child_post->post_title;
        $data['chroniktext'] = $child_post->fields['text-chronik'];
      }

    array_push($response, $data);
    // array_push($response, $result);
  }

How do I access the parent's childs?

Thanks in advance.
Theo

[Luo Yang]

Dear Theo,

In the latest version of Types plugin, you can use the new API function toolset_get_related_posts(), to get the related child posts, see our document:
https://toolset.com/documentation/customizing-sites-using-php/post-relationships-api/#toolset_get_related_posts
Query related posts by a set of conditions.

For example:

	/* Get childs 'chronikeintrag' from parent 'erinnerungsort' */
    $child_posts = $books = toolset_get_related_posts(
		$result->ID, // get posts related to this one
		array( 'erinnerungsort', 'chronikeintrag' ), // relationship between the posts
		'parent', // $result->ID is parent in given relationship
		20, 1, // pagination
		array(), // meta query filters?
		'post_object', // return type
		'child' //posts from the relationship should be returned
	);
	
    foreach ($child_posts as $child_post) {
        $data['chroniktitel'] =  $child_post->post_title;
        $data['chroniktext'] = get_post_meta($child_post->ID, 'text-chronik', true);
	}

[fabianT]

Perfect! Thanks a lot! Your example worked fine.