Display custom field & value correctly on page

Question

I have products with a list of custom field values which are loaded via CSV, but not all products have a value for every custom field as the field is not relevant to that product. I want to be able to call up every relevant custom field name and its value on the page for each product.

I am using this which does display the custom field value (only) on the page:

<?php echo get_post_meta( get_the_ID(), 'current_promotions', true ); ?>

However I would like to display the field name and value for each product where appropriate.

Can anyone help?

Answer 1

You can use <?php the_meta(); ?> to do this (id you want to print them inside the Loop).

From Codex:

This is a simple built-in function for displaying custom fields for the current post, known as the "post-meta" (stored in the wp_postmeta table). It formats the data into an unordered list (see output below).

It must be used from within The Loop or in a theme file that handles data from a single post (e.g. single.php). the_meta() will ignore meta_keys (i.e. field names) that begin with an underscore.

So this:

<p>Meta information for this post:</p>
<?php the_meta(); ?>

Will output this:

<ul class='post-meta'>
    <li><span class='post-meta-key'>your_key:</span> your_value</li>
    ... other fields
</ul>

Of course you can also do something like this (it's much easier to customize this code):

if ( $keys = get_post_custom_keys($post_id) ) {  // $post_id is ID of your post
    echo "<ul class='post-meta'>\n";
    foreach ( (array) $keys as $key ) {
        $keyt = trim($key);
        if ( is_protected_meta( $keyt, 'post' ) )
            continue;
        $values = array_map('trim', get_post_custom_values($key));
        foreach ( $values as $k=>$value ) {
            if ( $value == '' ) {  // or whatever is your way to find if value is irrelevant
                unset($values[$k]);
            }
        }
        $value = implode($values,', ');
        echo apply_filters('the_meta_key', "<li><span class='post-meta-key'>$key:</span> $value</li>\n", $key, $value);
    }
    echo "</ul>\n";
}