Supposing you want to have an image aside of each post in your post list page. The WordPress function get_the_post_thumbnail() is what you need. Make sure to set a featured image inside the edit post (or custom post) page.
If you forget to set the featured image inside a post, WordPress will consider as featured image the first uploaded image from your computer. Obviously if you do not have any image in the content of a post, the featured image for it will not exist.
What happens if you write a post and add images from the “WordPress media library” (without uploading images from your computer)?
Well, get_the_post_thumbnail() will not return any image at all.
If it is your blog/website it will not be a big problem, you will notice the error and you will fix it straight away.
But if you set up a WordPress website for some of your clients that are not really web oriented, the following solution will save you a lot of time (avoiding “not easy” support phone calls).
Copy the following code in your theme functions.php
// POST IMAGE
function get_default_post_image($size = 'thumbnail', $post_id = false){
global $post, $id;
$post_id = (int)$post_id;
if (!$post_id) $post_id = $post->ID;
$image = '';
if(has_post_thumbnail($post_id)) {
$image = get_the_post_thumbnail($post_id, $size);
} else {
$args = array(
'post_parent' => $post_id
, 'post_type' => 'attachment'
, 'post_mime_type' => 'image'
, 'post_status' => 'any'
, 'numberposts' => 1
, 'order' => 'ASC'
);
$attachments = get_children($args);
foreach($attachments as $attachment) {
//$attachment = array_shift($attachments);
$image = wp_get_attachment_image($attachment->ID, $size);
}
}
return $image;
}
function the_default_post_image($size = 'thumbnail', $post_id = false){
$img = get_default_post_image($size, $post_id);
if( empty($img) ){
$img = '<img src="'.get_bloginfo('stylesheet_directory').'/images/default_post_image.png" alt="no image" />';
}
echo $img;
}Make sure you add a “not available” image (/images/default_post_image.png) in your theme folder.
Then you will able to use the_default_post_image()
<?php if (have_posts()) : ?>
<?php while (have_posts()) : the_post(); ?>
...
<?php the_default_post_image(); ?>
...
<?php endwhile; ?>
<?php endif; ?>inside your theme (inside your post loop).
An alternative could be get_default_post_image()
<?php if (have_posts()) : ?>
<?php while (have_posts()) : the_post(); ?>
...
<?php echo get_default_post_image(); ?>
...
<?php endwhile; ?>
<?php endif; ?>Usage
<?php the_default_post_image( $size, $post_id ); ?>
the_default_post_image will return an HTML image (/images/default_post_image.png when not image is set in the post)
<?php echo get_default_post_image( $size, $post_id ); ?>
get_default_post_image() will return an HTML image as string and an empty string when not image is set in the post.
Parameters
size
(string/array) (Optional) Either a string keyword (thumbnail, medium, large or full) or a 2-item array representing width and height in pixels, e.g. array(32,32).
Default: ‘thumbnail’
post_id
(integer) (Optional) Post ID.
Default: Post ID
