[Support request] Quizzes Break on PHP 8

[Gevorg]

Hello,

We have LearnDash installed and its quizzes break after upgrading to PHP 8. I have contacted their support and after checking the error logs, they suggested contacting the GP support.

I would really appreciate it if you could take a look at this and see if there is a fix.
You can find more information in the form below.

Thank you.

[David]

Hi there,

the Stack Trace points to line 32 of the content-single.php template in your child theme.

This line: $mainCategorySlug = str_replace(' ', '-', strtolower($mainCategory));

For reference in this part of the code:

if ( $mainCategory == '' ) {
    $mainCategory = get_the_category_by_ID($subcategory->category_parent);
    $mainCategorySlug = str_replace(' ', '-', strtolower($mainCategory));
}

The strtolower function is expecting $mainCategory to be a string and for whatever reason it is not.

To debug comment out that line and var_dump the variable eg.

if ( $mainCategory == '' ) {
    $mainCategory = get_the_category_by_ID($subcategory->category_parent);
    //$mainCategorySlug = str_replace(' ', '-', strtolower($mainCategory));
    var_dump($mainCategory);
}

It may give you some idea of whats going wrong.

[Gevorg]

Hi David,

As always your codes are spot on and solve the problem. Thank you so much!

The only issue now is that there is an error message on the quiz pages:

object(WP_Error)#5500 (3) { [“errors”]=> array(1) { [“invalid_term”]=> array(1) { [0]=> string(11) “Empty Term.” } } [“error_data”]=> array(0) { } [“additional_data”:protected]=> array(0) { } }

Is there a way to get rid of that?

[David]

So thats what var_dump is doing which we can use to debug the issue.

Ill try and explain, so in your code:

if ( $mainCategory == '' ) {
    $mainCategory = get_the_category_by_ID($subcategory->category_parent);
    $mainCategorySlug = str_replace(' ', '-', strtolower($mainCategory));
}

This line: $mainCategory = get_the_category_by_ID($subcategory->category_parent); is loading the $mainCategory with a category term that is returned by the get_the_category_by_ID function.
The get_the_category_by_ID will either return the correct term name as a string or a wp_error as an array

This line uses:

$mainCategorySlug = str_replace(' ', '-', strtolower($mainCategory));

then uses the strtolower function to convert the $mainCategory string to lower case.

But as var_dump shows us the $mainCategory is returning an wp_error array so the strtolower function fails as it wants a string.

Try changing that code to:

if ( $mainCategory == '' ) {

    $mainCategory = get_the_category_by_ID($subcategory->category_parent);
    if ( ! is_wp_error( $mainCategory ) ) {
        $mainCategorySlug = str_replace(' ', '-', strtolower($mainCategory));
    }
    
}

This will check to make sure there is ! (not) a wp_error before doing the string replace.

[Gevorg]

David,

Thank you so much for your help! It works now. I appreciate it.

Have a great day.

[David]

You’re welcome.

[Author]

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