conditionally echo <br /> in meta box data loop

Question

I am working on a Thematic child theme and using the WPAlchemy Meta Box Class to create an 'Artwork Info' meta box that I want to conditionally echo like this at the end of each post:

Title
Medium
Dimensions
Additional Info

My instance of the class is defined like this in functions.php:

$prefix = 'wpf_';
$artinfo_mb = new WPAlchemy_MetaBox(array
(
    'id' => '_custom_meta', // underscore prefix hides fields from the custom fields area
    'title' => 'Artwork Info',
    'template' => STYLESHEETPATH . '/custom/artwork-meta.php',
    'context' => 'normal',
));

And here's an example of the HTML for each field, located in artwork_meta.php:

<label>Title</label> 
<p>
    <?php $mb->the_field('title'); ?>
        <input type="text" style="width:99%" name="<?php $mb->the_name(); ?>" value="<?php $mb->the_value(); ?>"/> 
</p>

I am using this function in functions.php to print the data in each post via an array of the fields:

function display_artwork_info() {

    global $artinfo_mb; 
    $artinfo_mb->the_meta();
    $values = array('title','medium','dimen','additional'); 

    echo the_content();  

    // loop through and conditionally echo the value with a line break
    foreach ($values as $val) {
        if ($val != ''){
            $mb->the_value($val);
            echo '<br />';
        }
    } 
} 
add_action('thematic_post', 'display_artwork_info');

All works fine except the foreach ($values as $val) always echoes the line breaks, even if the field's value contains no data. For example, if the 'medium' and 'additional info' fields are empty, the HTML echoes like this:

Title
<br />
<br />
Dimensions
<br />

Is there something wrong with my loop? Am I using the wrong WPAlchemy function to echo the meta data? Thanks in advance :)

Answer 1

$val will never == '' here, because $val is holding your field name, not the data. also, use get_the_value to have it returned, the_value will just echo the data out.

foreach ($values as $val) {
    if ($artinfo_mb->get_the_value($val) != ''){
        $artinfo_mb->the_value($val);
        echo '<br />';
    }
}