How to call an outside function within a WP loop and get the "next" item, but for specific slugs - php

Question

In my WordPress child theme workspace, I am trying to learn how to optimize my code below to be more efficient in its PHP process. I have 10 images total that I'm working with. I want any number of these images to be called onto different pages by slug. I know in PHP how to return once from a function, but how do I say in PHP...
"I want photos 1, 2, 6 to go to slugA"
"I want photos 2, 3, 5, 9 to go to slugB"
"I want photos 1, 7 to go to slugC"
etc...
This is what I have so far
//DEFINING ALL MY PHOTOS AND RETURNING THEM
function my_post_photos (
$mQuery = 1,
$image01 = "filler_01.jpg",
$image02 = "filler_02.jpg",
$image03 = "filler_03.jpg",
$image04 = "filler_04.jpg",
$image05 = "filler_05.jpg",
$image06 = "filler_06.jpg",
$image07 = "filler_07.jpg",
$image08 = "filler_08.jpg",
$image09 = "filler_09.jpg",
$image10 = "filler_10.jpg"
): string
{
$vars = get_defined_vars();
foreach ($vars as $key => $value) {
$placeholders[] = get_stylesheet_directory_uri() . '/dist/images/' . $value;
}
return $placeholders[$mQuery];
}
//FURTHER DOWN THIS SAME PAGE...WITHIN MY WP LOOP, CALLING THEM
<?php
$query = new WP_Query($args);
if ($query->have_posts()) :
//WITH THE BELOW $i, I AM FULLY AWARE THAT THE NUMBER OF PHOTOS LOADS IS DEPENDENT ON HOW MANY TIMES MY LOOP CYCLES. I'M COOL WITH THAT BECAUSE I'M EVENTUALLY GOING TO HAVE MORE PHOTOS THAN POSTS.
$i=1;
while ($query->have_posts()) : $query->the_post();
$current_page = sanitize_post($GLOBALS['wp_the_query']->get_queried_object());
$slug = $current_page->post_name;
?>
<?php
if ($slug == "slugA") {
?>
<div>
<h6>
<!-- //THIS FUNCTION LOADS EACH PHOTO PERFECTLY FINE, BUT HOW CAN I ONLY RETURN PHOTOS 1, 2, 6 HERE? -->
<img src="<?php echo my_career_placeholder($i); ?>" border="0" alt="">
</h6>
</div>
<?php
} elseif ($slug = "slugB") {
//HOW CAN I RETURN ONLY PHOTOS 2, 3, 5, 9 HERE?
} elseif ($slug = "slugC") {
//HOW CAN I RETURN ONLY PHOTOS 1, 7 HERE?
}
?>
<?php
$i++;
endif;
endwhile;
endif;
wp_reset_postdata();
?>

Answer 1

Looking at your code as a whole, I think your main function could be rewritten as follows:
function my_post_photos(...$indexes): array
{
$pathPrefix = get_stylesheet_directory_uri().'/dist/images/';
$placeholders = [
$pathPrefix.'filler_01.jpg',
$pathPrefix.'filler_02.jpg',
$pathPrefix.'filler_03.jpg',
$pathPrefix.'filler_04.jpg',
$pathPrefix.'filler_05.jpg',
$pathPrefix.'filler_06.jpg',
$pathPrefix.'filler_07.jpg',
$pathPrefix.'filler_08.jpg',
$pathPrefix.'filler_09.jpg',
$pathPrefix.'filler_10.jpg',
];
$ret = [];
foreach ($indexes as $index) {
if (isset($placeholders[$index])) {
$ret[] = $placeholders[$index];
}
}
return $ret;
}
This would allow you to call it and pass as many indexes in as you want by doing my_post_photos(3,5), which would return an array that you could loop over.
Demo here: https://3v4l.org/8aq6d
Additional optimizations could be done if you truly name your images in that consistent manner, but I'm just keeping this simple for now.
edit
Based on your comments, I think you want to call the function in the loop and get the "next" item, but for the specific slug.
If that's right, one way to do this would be to create a second array that maps slugs to image indexes. You can then use static with that array which means that subsequent calls to the function won't recreate the array, but instead use the first one. Lastly, you can use array_shift which gets you the first item from an array and actually removes that index from the array. (The function array_shift is considered non-performant for large arrays, if I understand things correctly, but I don't think you'll notice that here at all.)
The code below changes this back to returning a string (or null), and can be called repeatadly with a known-slug to get the "next" item. If you'd ever have more posts than images you could take the "next" and append it to the end of the array giving you a circular pool, too.
function my_post_photos(string $slug): ?string
{
$pathPrefix = get_stylesheet_directory_uri().'/dist/images/';
$placeholders = [
$pathPrefix.'filler_01.jpg',
$pathPrefix.'filler_02.jpg',
$pathPrefix.'filler_03.jpg',
$pathPrefix.'filler_04.jpg',
$pathPrefix.'filler_05.jpg',
$pathPrefix.'filler_06.jpg',
$pathPrefix.'filler_07.jpg',
$pathPrefix.'filler_08.jpg',
$pathPrefix.'filler_09.jpg',
$pathPrefix.'filler_10.jpg',
];
// Mapping of slugs to placeholders
// NOTE: This array is created static so that it only ever
// gets created once in the lifetime of the PHP request
static $slugToPlaceholders = [
'slugA' => [1, 2, 6],
'slugB' => [2, 3, 5, 9],
'slugC' => [1, 7],
];
// Unknown slug, return null
if(!isset($slugToPlaceholders[$slug])){
return null;
}
// Grab the next unused index, and remove it from the array
$nextIndex = array_shift($slugToPlaceholders[$slug]);
// Return either the image or nothing if we're out of indexes
return $placeholders[$nextIndex] ?? null;
}
Demo: https://3v4l.org/JDKOH