**this is code exemple
I need a gallery of images, small photos down, clicking shows an image above. So far I can not open large image. **
<li><a data-image-id="'.$photo_id.'" href="'. get_permalink($photo_id).'">
<img data-image-id="'.$photo_id.'" class="thumbnail" src="'.get_the_post_thumbnail('small_thumbnail').'"></a></li>
There no WordPress function wp_get_attachment_src when you want to get answer you should clear your questions and also descriptive
I am giving you explanation of you question.
you what is difference wp_get_attachment_url / wp_get_attachment_src / get_post_thumbnail_id?
wp_get_attachment_url($id)
Returns a full URI for an attachment file or false on failure.
Here id is attachment post id
Example
echo wp_get_attachment_url( $id );
echo wp_get_attachment_url( 12 );
$example_url = wp_get_attachment_url( get_post_thumbnail_id() );
echo '<div style="background-image:url('.$example_url.');"></div>';
wp_get_attachment_image_src()
return array value of image attribute
Example
wp_get_attachment_image_src( int $attachment_id, string|array $size="thumbnail", bool $icon = false )
$image_attributes = wp_get_attachment_image_src( $attachment_id = 8 );
if ( $image_attributes ) : ?>
<img src="https://wordpress.stackexchange.com/questions/261283/<?php echo $image_attributes[0]; ?>" width="<?php echo $image_attributes[1]; ?>" height="<?php echo $image_attributes[2]; ?>" />
<?php endif; ?>
get_post_thumbnail_id()
return featured image id
Example:
get_post_thumbnail_id($post_id)
$post_thumbnail_id = get_post_thumbnail_id( $post_id );
Now Solution of your problem
I guess $photo_id is your post id
<li><a data-image-id="'.$photo_id.'" href="'. get_permalink($photo_id).'">
<img data-image-id="'.$photo_id.'" class="thumbnail" src="'.get_the_post_thumbnail( $photo_id, 'thumbnail', array( 'class' => 'alignleft' ) );.'"></a>
</li>
for more information follow the codex:
get_post_thumbnail_id()
wp_get_attachment_image_src()
wp_get_attachment_url()