How do I use “if field exists” with $curauth?

Question

I've added some extra $curauth fields to the user profile page via ths method:

function change_contactmethod( $contactmethods ) {

$contactmethods['twitter'] = 'Twitter URL';

// more $contactmethods go here

return $contactmethods;
 }

add_filter('user_contactmethods','change_contactmethod',10,1);

And they are displayed this way on the author.php template, which only displays the link if it is entered in te user profile:

<?php echo $curauth->twitter; ?>

But what I need to do is determine if the curauth field exists before display, as I want to turn the twitter URL into a linked image. Calling $curauth->twitter; as above with a linked image still displays the image if no link is entered in the users profile.

This is what I'm trying with no luck:

<?php $my_post_meta = get_post_meta($post->ID, 'twitter', true);
if ( ! empty ( $my_post_meta ) )
    echo '<a href=" '.$my_post_meta.' "><img src="<?php bloginfo(\'template_url\'); ?>/images/twitter.png"></a>'; ?>

Update 12/23/11 - This now works:

<?php if ( !empty( $curauth->twitter ) ) { echo '<a href=" ' . $curauth->twitter . '"><img src="' . get_bloginfo('template_url') . '/images/twitter.png"></a>'; } ?>

Answer 1

Use the empty() check on them.

if ( !empty( $curauth->twitter ) ) {
  // do stuff 
}

This is best practice since empty avoids the property not existing error.

Answer 2

get_post_meta is used for posts and won't retrieve author information.

You'll need to use get_the_author_meta('twitter');.

In this case on the author.php page :

$curauth = (isset($_GET['author_name'])) ? get_user_by('slug', $author_name) :  get_userdata(intval($author));
    if ($curauth->twitter)  {
        echo '<a href=" ' . $curauth->twitter . '"><img src="' . get_bloginfo('template_url') . '/images/twitter.png"></a>';
    }