Using DocLister prepare to Enrich Rows with Data from Another Table

DocLister’s prepare callback is one of the cleanest ways to enrich row data before rendering. It is especially useful when the listing itself comes from one source, but related assets such as images live in another table.

Example setup

[!DocLister?
&controller=`avto`
&idType=`documents`
&prepare=`.getFotoAvto`
&tpl=`@CODE: ... [+image-src+] ...`
&display=`10`
&paginate=`pages`!]

The callback then reads a custom table and appends HTML or a derived value into the row data:

$result = $modx->db->select('*', 'my_img_avto');
while ($row = $modx->db->getRow($result)) {
    if ($row['id_ad'] == $data['id']) {
        $tmp .= '<img src="' . $modx->runSnippet('phpThumb', [
            'input' => $row['src'],
            'options' => 'w=150,h=76,far=C,bg=FFFFFF'
        ]) . '">';
    }
}
$data['image-src'] = $tmp;
return $data;

Why this helps

The template stays focused on presentation while the callback handles the extra lookup logic. That is much easier to maintain than scattering custom SQL and image logic directly into snippets or chunks.

Performance warning

If the callback scans a whole related table for every row, it will slow down on large datasets. For bigger projects, narrow the related query up front or pre-index the related records by the current document IDs.