Common php function called by other functions - php

Question

Hello I would like to create two functions with different parameter but with a same common function. Here's my example...
The common function :
function my_responsive_pictures($post_id){
// Get alt text or set the $alt_text variable to the post title if no alt text exists
$alt_text = get_post_meta($attachment_id, '_wp_attachment_image_alt', true);
if ( !$alt_text ) { $alt_text = esc_html( get_the_title($post_id) ); }
// Get the info for each image size including the original (full)
$thumb_original = wp_get_attachment_image_src($attachment_id, 'slideshow');
$thumb_large = wp_get_attachment_image_src($attachment_id, 'slideshow-lg');
$thumb_medium = wp_get_attachment_image_src($attachment_id, 'slideshow-md');
$thumb_small = wp_get_attachment_image_src($attachment_id, 'slideshow-xs');
// Create array containing each image size + the alt tag
$thumb_data = array(
'thumb_original' => $thumb_original[0],
'thumb_large' => $thumb_large[0],
'thumb_medium' => $thumb_medium[0],
'thumb_small' => $thumb_small[0],
'thumb_alt' => $alt_text
);
// Echo out <picture> element based on code from above
echo '<picture>';
echo '<!--[if IE 9]><video style="display: none;"><![endif]-->'; // Fallback to <video> element for IE9
echo '<source srcset="' . $thumb_data['thumb_large'] . ', ' . $thumb_data['thumb_original'] . ' x2" media="(min-width: 800px)">';
echo '<source srcset="' . $thumb_data['thumb_medium'] . ', ' . $thumb_data['thumb_large'] . ' x2" media="(min-width: 400px)">';
echo '<source srcset="' . $thumb_data['thumb_small'] . ', ' . $thumb_data['thumb_medium'] . ' x2">';
echo '<!--[if IE 9]></video><![endif]-->'; // Fallback to <video> element for IE9
echo '<img srcset="' . $thumb_data['thumb_small'] . ', ' . $thumb_data['thumb_medium'] . ' x2" alt="' . $thumb_data['thumb_alt'] . '">';
echo '</picture>';
}
Another one which calls the common function :
function my_responsive_thumbnail($post_id){
// Get the featured image ID
$attachment_id = get_post_thumbnail_id($post_id);
my_responsive_pictures();
}
And a second one with other parameters $attachment_ID :
function my_responsive_acfthumbnail($post_id){
// Get the featured image ID
$attachment_id = get_field('image_bandeau');
my_responsive_pictures();
}
Nothing happens :(. What do I do wrong ? Thanx for your help...

Answer 1

Your function is expecting a parameter, and when you're calling it here
my_responsive_pictures();
you aren't passing anything.
You also have to call the my_responsive_thumbnail() function before it's going to make the subsequent calls to your "common" function.

Answer 2

There are a few issues with this code. The first thing we need to look at is the main function.
function my_responsive_pictures($post_id){
Your function definition doesn't give $post_id a default value therefore it's required any time you call the function. By attempting to call the function without passing an the argument you'll trigger an error.
$alt_text = get_post_meta($attachment_id, '_wp_attachment_image_alt', true);
if ( !$alt_text ) { $alt_text = esc_html( get_the_title($post_id) ); }
Here you're referring to $attachment_id which hasn't been set. When it's not found you're then getting the title of the post.
For this to work you'll need to set two parameters for the function.
function my_responsive_pictures( $attachment_id, $post_id ) {
Any time we call this function we need to pass in the $attachment_id (ID of the image) and $post_id (ID of the post).
Next up we need to modify the functions that ultimately call the main function.
function my_responsive_thumbnail( $post_id ) {
// Get the featured image ID
$attachment_id = get_post_thumbnail_id( $post_id );
// Now that we have the featured image ID, we really ought
// to do some error checking. Let's assume that all went well.
my_responsive_pictures( $attachment_id, $post_id );
}
This next function requires more attention. Remember that you're calling these functions with the post ID. You need to let get_field() know the ID of the post it should retrieve the image for.
function my_responsive_acfthumbnail( $post_id ) {
// Get the featured image ID
$attachment_id = get_field( 'image_bandeau', $post_id );
my_responsive_pictures( $attachment_id, $post_id );
}
Example usage:
my_responsive_acfthumbnail( get_the_ID() );
You may also want to consider setting a default for the post ID so you don't need to pass it in when retrieving an image for the current post you're viewing.
Finally, consider the level of duplication between the functions which call my_responsive_pictures. You'll want to check the attachment ID is valid so the functions are likely to become larger with only 1 line that's different.
Further information on get_field(): https://www.advancedcustomfields.com/resources/get_field/