php code crashes site - possible syntax error

Question

In order to query products based on custom fields, from the plugin advanced custom fields, i have to use this wp query script, to query it correctly.

However, when i copied this script, changed the needed values, and inserted it into functions.php, it crashes the site.

I believe its a parse or syntax error because its using a lot of . I have tried removing some of them, still no results. When all the other scripts above it has been removed (irrelevant), then it looks like this:

    <?php
<?php
add_action( 'wp_ajax_posts_by_brand_action', 'posts_by_brand_action_callback' );

function posts_by_brand_action_callback() {
    global $wpdb; // this is how you get access to the database

    $brand = $_POST['brand'];

        echo $whatever;

  // ----- START OF BRAND FILTER CODE


  // args
  $args = array(
    //'numberposts' => -1,
    //'post_type'       => 'event',
    'meta_key'      => 'brand',
    'meta_value'    => $brand
  );


  // query
  $the_query = new WP_Query( $args );

  <?php if( $the_query->have_posts() ): ?>
    <ul>
    <?php while( $the_query->have_posts() ) : $the_query->the_post(); ?>
      <li>
        <a href="<?php the_permalink(); ?>">
          <?php the_title(); ?>
        </a>
      </li>
    <?php endwhile; ?>
    </ul>
  <?php endif; ?>

  <?php wp_reset_query();    // Restore global post data stomped by the_post(). ?>

  // ------ END OF BRAND FILTER CODE

    wp_die(); // this is required to terminate immediately and return a proper response
}
?>

How do i go a about this? Would it be correct to say, that shouldn't be used inside an ?

Answer 1

It's hard to debug only seeing a portion of your code.

For starters, you've got two <?php opening tags at the top which would certainly cause an error. But I think that's leftover from your copy and paste.

• Look at your php server log which will tell you what file and line number the error is occurring.
• Put the following in your wp-config.php file which will print all errors in your browser. Then you won't have to access the php log directly.

Code to add:

define( 'WP_DEBUG', true );

WordPress Debugging Guide

Answer 2

Why are you opening so many php tags without any reason? Here is the reviewed code, please check if it works:

<?php
add_action( 'wp_ajax_posts_by_brand_action', 'posts_by_brand_action_callback' );

function posts_by_brand_action_callback() {
    global $wpdb; // this is how you get access to the database

    $brand = $_POST['brand'];

    echo $whatever;

  // ----- START OF BRAND FILTER CODE


  // args
  $args = array(
    //'numberposts' => -1,
    //'post_type'       => 'event',
    'meta_key'      => 'brand',
    'meta_value'    => $brand
  );


  // query
  $the_query = new WP_Query( $args );

  if($the_query->have_posts() ):
?>
    <ul>
    <?php while( $the_query->have_posts() ) : $the_query->the_post(); ?>
      <li>
        <a href="<?php the_permalink(); ?>">
          <?php the_title(); ?>
        </a>
      </li>
    <?php endwhile; ?>
    </ul>
  <?php
  endif;

  wp_reset_query();  // Restore global post data stomped by the_post().

  // ------ END OF BRAND FILTER CODE

    wp_die(); // this is required to terminate immediately and return a proper response
}
?>