"Notice: Undefined index: und in include()"

Question

Since this morning, I get this message on my website.

It says the error is on line 7 in my template file, but when I look at the line 7 the code on it is <?php if (!$page): ?>.

My template file looks like the following.

<div id="node-<?php print $node->nid; ?>" class="<?php print $classes; ?>">
  <div class="node-inner">
    <?php if (!$page): ?>
      <h2<?php print $title_attributes; ?>>      
      <?php if (($type == "article") && ($node->field_add_taxonomy_tag_articles[$node->language][0]['tid'] == 26)): ?>
        <a href="/discoveries#node-<?php print $node->nid; ?>"><?php print $title; ?></a></h2>
      <?php else:?>
        <a href="<?php print $node_url; ?>"><?php print $title; ?></a></h2>
      <?php endif; ?>
    <?php endif; ?>
    <?php print $user_picture; ?>
    <?php if ($display_submitted): ?>
      <span class="submitted"><?php print $date; ?> Ñ <?php print $name; ?></span>
    <?php endif; ?>
    <div class="content">
      <?php
        hide($content['comments']);
        hide($content['links']);
        print render($content);
      ?>
      <?php if (!empty($content['links'])): ?>      
        <span class="links">
          <?php print render($content['links']); ?>
        </span>
      <?php endif; ?>
    </div>      
    <?php if (!empty($content['links']['terms'])): ?>
      <div class="terms">
        <?php print render($content['links']['terms']); ?>
      </div>
    <?php endif;?>  
  </div> <!-- /node-inner -->
</div> <!-- /node-->
<?php print render($content['comments']); ?>'

Answer 1

The line that is causing that error message is the following one.

<?php if (($type == "article") && ($node->field_add_taxonomy_tag_articles[$node->language][0]['tid'] == 26)): ?>

'und' is the value for the constant LANGUAGE_NONE, which is used for $node->language, when the node is language-neutral.

When you want to obtain the value of a field, you should use field_get_items(), as in the following code.

<?php $items = field_get_items('node', $node, 'field_add_taxonomy_tag_articles'); ?>
<?php if (($type == "article") && ($items[0]['tid'] == 26)): ?>