make duplicate elements if their number is less than 4 and they are not empty

Question

I have a slider for scrolling through images, and I add all the images to the slider through php

The situation is that the slider needs at least 4 images to work, and I wrote the corresponding code that copies and pastes the images, if we add only one or two

Here is the working code

<?php if (count($images) < 4) { ?>
    <?php
    $images = array_merge($images, $images);
    $images = array_merge($images, $images);
    $images = array_slice($images, 0, 4);

    foreach ($images as $image) {
        if ($image->image_id) { ?>
            <div class="slider-image">
                <img src="<?= $image->url ?>" alt="<?= $image->name ?>">
            </div>
        <?php } ?>
    <?php } ?>
<?php } ?>

And there is this line

if ($image->image_id)

That is, I may have a situation that such an image is not in the database, and so that there are no errors, I added the appropriate check

So, if I have an image that is not in the database, then this copy code does not work, since it copies an empty image, which is then not displayed

$images = array_merge($images, $images);
$images = array_merge($images, $images);
$images = array_slice($images, 0, 4);

How can I take into account the factor that the picture is not in the database and correct the code for copying? Or do I need to use another implementation here?

Answer 1

I presume your $images is not empty and is a regular list (has sequental zero-based indices). Just populate the images array in the loop as:

$images = [0,1];
$i = 0;
while( count( $images ) < 4 )
    $images[] = $images[ $i++ ];


print_r($images); # [0,1,0,1]


/*
For given initial arrays we will get following results:

[0] -> [0,0,0,0]
[0,1] -> [0,1,0,1]
[0,1,2] -> [0,1,2,0]
[0,1,2,3] -> [0,1,2,3]
*/

If you have some dummy images objects - filter them out first:

$images = array_filter($images, fn($image) => !empty($image->image_id) );