php - How to make this code valid only when the value exists?

very new here to php and wordpress coding (1 day lol). This is my code so far, the problem is that when there is no value assigned to this attribute I receive and error message. I know I need something that says if the value exists then display the rest of the code but not sure how to go about adding that. This is for a woocommerce product attribute btw.

Code so far:

$collection_values = get_the_terms( $product->id, 'pa_collection');

    foreach ($collection_values as $collection_value){
        echo '<h2 class="collection_title"><a href="'.get_term_link($collection_value->slug, $collection_value->taxonomy).'">'.$collection_value->name.'</a></h2>';
    }

Error message:

Warning: Invalid argument supplied for foreach() in /app/public/wp-content/themes/savoy/woocommerce/single-product/title.php on line 21

EDIT： I am adding this above the product title in the title.php page.

very new here to php and wordpress coding (1 day lol). This is my code so far, the problem is that when there is no value assigned to this attribute I receive and error message. I know I need something that says if the value exists then display the rest of the code but not sure how to go about adding that. This is for a woocommerce product attribute btw.

Code so far:

$collection_values = get_the_terms( $product->id, 'pa_collection');

    foreach ($collection_values as $collection_value){
        echo '<h2 class="collection_title"><a href="'.get_term_link($collection_value->slug, $collection_value->taxonomy).'">'.$collection_value->name.'</a></h2>';
    }

Error message:

Warning: Invalid argument supplied for foreach() in /app/public/wp-content/themes/savoy/woocommerce/single-product/title.php on line 21

EDIT： I am adding this above the product title in the title.php page.

• php

Share Improve this question edited Dec 8, 2018 at 18:46 panther888 asked Dec 8, 2018 at 18:15 panther888panther888 111 bronze badge 2

• See the example in the documentation. – Milo Commented Dec 8, 2018 at 18:19
• Hey Milo, thanks for the tip. This worked in terms of showing the attribute value only when it exists but now my title is no longer showing (I'm adding this code above the product title). The code that calls the attribute archive link also no longer works. – panther888 Commented Dec 8, 2018 at 18:45

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2 Answers 2

Sorted by: Reset to default 0

If we refer to the documentation, we see that get_the_terms returns an array, false, or a WP_Error object. So in our code we'll add a check if $collection_values exists (it's not false), and it's not an error, then we'll know it has to be an array, and it's safe to run a foreach loop on it.

$collection_values = get_the_terms( $product->id, 'pa_collection');

if ( $collection_values && ! is_wp_error( $collection_values ) ){
    foreach ($collection_values as $collection_value){
        echo '<h2 class="collection_title"><a href="'.get_term_link($collection_value->slug, $collection_value->taxonomy).'">'.$collection_value->name.'</a></h2>';
    }
}

This code worked for me:

      $collection_values = get_the_terms( $product->id, 'pa_collection');
    if( !empty($collection_values) ) :
    foreach ($collection_values as $collection_value){
        echo '<h2 class="collection_title"><a href="'.get_term_link($collection_value->slug, $collection_value->taxonomy).'">'.$collection_value->name.'</a></h2>';
    }

endif;