I needed to pass an image to a Pinterest plugin in posts without a featured image so I wrote a little function to get the id of the first picture in a post. This code is in the loop-single.php where the sharing buttons are located.

After a lot of reading and trial and error I got this code to work.

<?php if ( has_post_thumbnail()) {
                $thumb_for_pinterest = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'full' );
                } else {
 
                    $attachments = get_children( array(
                'post_parent'    => get_the_ID(),
                'post_type'      => 'attachment',
                'numberposts'    => 1, // show all -1
                'post_status'    => 'inherit',
                'post_mime_type' => 'image',
                'order'          => 'ASC',
                'orderby'        => 'menu_order ASC'
                ) );
                foreach ( $attachments as $attachment_id => $attachment ) {
                    $thumb_for_pinterest = wp_get_attachment_image_src($attachment_id, 'full' );
                    }
                } ?>

My question is this. Why do I need to use a foreach to get the attachment_id? Specifically, what is this line doing?

I have looked at this quite a bit and I can't tell if my knowledge is lacking in wordpress or php or both. I believe an associative array is being returned with only 1 object in it. However, when I tried to just pop the object out of the array and use it I got lots of errors. Only by putting it in the foreach could I get the image id out.

Is there an easier way to get the attachment_id of the first image in a post?

I have read a lot of questions and googled this quite extensively, but couldn't understand it completely. Sorry if this a rookie question, I don't want to waste anyones time.

PS - the Pinterest code (or rather AddThis code) that uses the attachment_id is here

<a class="addthis_button_pinterest_pinit" pi:pinit:url="<?php the_permalink(); ?>" pi:pinit:description="<?php the_title(); ?>" pi:pinit:media="<?php echo $thumb_for_pinterest[0]; ?>" pi:pinit:layout="horizontal"></a>

I needed to pass an image to a Pinterest plugin in posts without a Featured Image so I wrote a little function to get the id of the first picture in a post. This code is in the loop-single.php where the sharing buttons are located.

if ( has_post_thumbnail()) {
    $thumb_for_pinterest = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'full' );
} else {
    $attachments = get_children( array(
        'post_parent'    => get_the_ID(),
        'post_type'      => 'attachment',
        'numberposts'    => 1, // show all -1
        'post_status'    => 'inherit',
        'post_mime_type' => 'image',
        'order'          => 'ASC',
        'orderby'        => 'menu_order ASC'
    ) );
     
    foreach ( $attachments as $attachment_id => $attachment ) {
        $thumb_for_pinterest = wp_get_attachment_image_src($attachment_id, 'full' );
    }
}

My question is this: why do I need to use a foreach to get the attachment_id?
Specifically, what is this line doing?

I believe an associative array is being returned with only 1 object in it. However, when I tried to just pop the object out of the array and use it I got lots of errors. Only by putting it in the foreach could I get the image id out.

Is there an easier way to get the attachment_id of the first image in a post?

I have read a lot of questions and googled this quite extensively, but couldn't understand it completely.