Use a node's cck field in a block

You're definitely on the right track.

PHP has a handy function for checking whether a variable has meaningful content: empty(foo). You can read about empty() in the PHP documentation, but it returns true if foo is unset, null, an empty string, the number 0, an empty array, false, etc. Thus, !empty(foo) will be true whenever foo has meaningful content.

Try something like this:

<?php

  $skype_name = check_plain($node->field_skypename[0][value]); // Use check_plain as a security measure.
  if (!empty($skype_name)) { // Do the following only if $skype_name is not empty:
    print '<a href="skype:'. $skype_name .'?call">Call</a>';
  }

?>

The reason to use check_plain is that $node->field_skype[0][value] presumably contains (or could contain) user input, and you shouldn't print user input directly to output. You should always run it through some function that filters it first. Otherwise, you open security holes in your site.

The most Drupalicious way to generate links is with l(), but I don't know how to get it to recognize skype as a protocol.

Fantastic. Sorry I couldn't help you resolve the issue more quickly.

Here's a cleaner version (without the debugging code) for you when you get back from dancing in the streets:

<?php

if (arg(0) == 'node' && is_numeric(arg(1))) {
  if ($node = node_load(arg(1))) {
    if ($node->type == 'contact') {
      $skype_name = check_plain($node->field_skypename[0]['value']);
    }
  }

  if (!empty($skype_name)) {
    print '<a href="skype:'. $skype_name .'?call">Call</a>';
  }
}

?>

For the record, here's what the code does:

1. Check whether the original path (i.e., not the alias created by pathauto) is node/NID, where NID is the numeric node ID of the node we're looking at.
2. Tries to load the node with ID NID, failing "silently" (without doing anything) if it can't.
3. Check whether $node is a Contact node, failing "silently" if it isn't. This prevents the block from showing any content on non-Contact nodes.
4. Get the skypename from the CCK field, using check_plain to protect against malicious code.
5. If skypename contains meaningful content (i.e., isn't empty, etc.), print a link to call that person on Skype.

Among the things that caused us problems in trying to figure this out (and thus things to check if you're having similar problems):

• $node is not defined when the block is constructed, so we need to do it ourselves.
• arg() ignores path aliases, so it saw arg(0) as 'node' and arg(1) as '14', not 'contact' and 'jimbo', even when the browser shows the path as 'contact/jimbo'.

But how would you render the field properly, as defined in the content type display settings?

For example, when the value is a node or user reference, it can be rendered as a view.