Dynamically set front page featured image from first image in latest post's ACF

• TothDigital

• December 30, 2018 at 8:55 am

My front page template is set to display the full content of the latest post using WP_Query and a custom page template. Now I want the home page featured image to dynamically change every time a new post is published. The goal is to show the first image from the latest post’s ACF gallery when sharing the home page on social media.

I am not great with PHP so Im not sure if I am even approaching this the right way. So far this code does nothing. Do I need to hook my function to something else? Where am I going wrong?

// Set front page featured image to first image in surf report cpt ACF gallery

function set_home_featured_image_from_ACF_gallery () {

    global $post;

    // Get front page id
    $frontpage_id = get_option( 'page_on_front' );

    // Get id of latest post
    $recent_posts = wp_get_recent_posts( array( 'numberposts' => '1' ) );

    // Set $post_id variable to latest post id
    $post_id = $recent_posts[0]['ID']; 

    if ( is_front_page() ) {

        /* Get the home page thumbnail (should i be getting the home page thumbnail here or the post thumbnail of the latest post?) */

        $has_thumbnail = get_the_post_thumbnail($frontpage_id);

            // Get the first image from the ACF gallery in the latest post
            $images = get_field('surf_report_gallery', $post_id, false);
            $image_id = $images[0];

            if ( $image_id ) {
          // Set home page featured image to first ACF image 
          set_post_thumbnail( $frontpage_id, $image_id );
        }       
    }   
}
add_action( 'save_post', 'set_home_featured_image_from_ACF_gallery' );

Also, every time I share the home page it wants to display an image that I have removed from the site completely. Even when I manually add a featured image in the page editor. Weird…

• John Huebner

• January 3, 2019 at 10:59 am

When working with ACF it is almost always best to use use acf/save_post https://www.advancedcustomfields.com/resources/acf-save_post/. There is no guarantee that ACF will have saved values using WP save_post hook.

add_action('acf/save_post', 'set_home_featured_image_from_ACF_gallery');
function set_home_featured_image_from_ACF_gallery($post_id) {
  // still need to do this
  $recent_posts = wp_get_recent_posts(array( 'numberposts' => '1'));
  if ($post_id != $recent_posts[0]->ID) {
    // this post is not the most recent post
    return;
  }
  $frontpage_id = get_option('page_on_front');
  $images = get_field('surf_report_gallery', $post_id, false);
  $image_id = 0;
  if (!empty($images)) {
    $image_id = $images[0];
  } else {
    // backup, use the post featured image?
    $image_id = get_post_thumbnail_id($post_id);
  }
  if ($image_id) {
    // remove the if statement if you want to remove the feature image
    // if a new image is not found
    set_post_thumbnail($frontpage_id, $image_id);
  }
}