using the loop in custom meta is messing up 'add new' post type

Question

When I use the following code in a (wpalchemy) custom meta box, everything works fine. That is until I pressed 'add new'. At this point, the title, slug, featured image, etc.. are being pre-populated with the content from my 'products' post type.

The code builds a drop down within my 'case studies' post-type, and populates it with post titles/ids from my 'projects' post type.

How can I use the loop in the backend like this without messing stuff up. I tried with get_posts as well as WP_Query.

global $post;
$args = array( 'post_type' => 'projects', 'posts_per_page' => 200 );
$custom_posts = get_posts($args);

foreach($custom_posts as $post) : setup_postdata($post);
  echo '<option value="' . get_the_id() . '"';
  echo '>' . get_the_title() . '</option>' . "\n";
endforeach;

Edit: A little more background:

I'm using the wpalchemy class for custom meta boxes. The following code is included in my functions.php file, after /wpalchemy/MetaBox.php https://github.com/farinspace/wpalchemy/blob/dev/wp-content/wpalchemy/MetaBox.php

$assoc_project = new WPAlchemy_MetaBox(array(
    'id' => '_assoc_project',
    'title' => 'Associated Project',
    'template' => get_stylesheet_directory() . '/metaboxes/case-studies-assoc_proj-meta.php',
    'types'=> array('case-studies')
));

Edit 2: Update

I've tried and replicated this problem accross multiple browsers on my PC, but I just had a co-worker try on Ffox/mac and they don't have the problem. I don't understand why this would be platform specific - but there it is...

Answer 1

After you create a custom loop, you need to restore the global post variables with wp_reset_query().

Answer 2

Ok, I sorted this out myself. Instead of get_posts or WP_Query I used a custom select query as explained here

My revised code:

<select name="<?php $mb->the_name(); ?>">
    <?php 
    global $wpdb;
    $selected = ' selected="selected"';
    $querystr = "
       SELECT $wpdb->posts.post_title,  $wpdb->posts.ID
       FROM $wpdb->posts
       WHERE $wpdb->posts.post_type = 'projects' 
       AND $wpdb->posts.post_status = 'publish' 
       ORDER BY $wpdb->posts.post_name DESC
    ";
    $assocProjQuery = $wpdb->get_results($querystr, OBJECT);
    foreach($assocProjQuery as $ap):
        echo '<option value="' . $ap->ID . '"';
            if ($mb->get_the_value() == $ap->ID ) echo $selected;
        echo '>' . $ap->post_title . '</option>' . "\n";
    endforeach;
    ?>
</select>