For MODX CMS, produces an A to Z listing of selected resources using pdoTools

modx.snippet.pdoAtoZ.php

<?php
/**
 * pdoAtoZ
 *
 * DESCRIPTION
 *
 * Produces an A to Z listing of selected resources using pdoTools
 * See https://www.med.upenn.edu/modx-blog/a-to-z-list.html for more info
 * 
 * REQUIRES pdoTools PACKAGE
 *
 * SELECTION PROPERTIES:
 *
 * available pdoTools properties
 * (see pdoResources doc for more info: https://docs.modx.pro/en/components/pdotools/snippets/pdoresources)
 * 
 * &parents integer optional. Default: 0
 * &select string optional. Default: ''
 * &includeTVs string optional. Default: ''
 * &processTVs string optional. Default: ''
 * &limit integer optional. Default: 10
 * &sortby string optional. Default: 'pagetitle'
 * 
 * TEMPLATE PROPERTIES:
 * 
 * &itemTpl string, the name of the chunk to use as a template for each resource in the list, required.
 *
 * USAGE:
 * 
 *  Create a chunk to use for &itemTpl, a-to-z-tpl, for example:
 * 
 * <p>
    <a target="_blank" href="[[~[[+id]]]]">[[+pagetitle]]</a>
    <br>
    [[+introtext:!empty=`[[+introtext:nl2br]]<br>`]]
    <a href="[[~[[+id]]]]">More Info</a>
   </p>
 *
 *  [[pdoAtoZ?
        &select=`{"modResource":"id,pagetitle,introtext"}`
        &itemTpl=`a-to-z-tpl`
        &limit=`0`
    ]]
 *
 */
 
$parents = $modx->getOption('parents', $scriptProperties, 0);
$select = $modx->getOption('select', $scriptProperties, 0);
$includeTVs = $modx->getOption('includeTVs', $scriptProperties, '');
$processTVs = $modx->getOption('processTVs', $scriptProperties, '');
$limit = $modx->getOption('limit', $scriptProperties, '10');
$sortby = $modx->getOption('sortby', $scriptProperties, 'pagetitle');

$itemTpl = $modx->getOption('itemTpl', $scriptProperties, false);

if (!$itemTpl) return;

$pdo = $modx->getService('pdoFetch');

//Get collection of resources
$items = $pdo->getCollection('modResource', array(
    'published' => true,
    'deleted' => false
), array(
    'parents' => $parents,
    'select' => $select,
    'includeTVs' => $includeTVs,
    'processTVs' => $processTVs,
    'limit' => $limit,
    'sortby' => $sortby,
    'sortdir' => $sortdir,
));

//create an array keyed with alphabet letters
$alphas = range('A', 'Z');
$alphaGroups = array();
foreach($alphas as $key=>$value){
    $alphaGroups[$value] = array();
}

// organize the resources by first letter
foreach ($items as $item) {
    $firstLetter = strtoupper(substr ( $item['pagetitle'] , 0, 1));
    $item['url'] = $modx->makeUrl($item['id']);
    // check to see if first letter is a letter, if not don't do anything with it
    if (!preg_match('/[A-Z]/', $firstLetter)) continue;
    array_push($alphaGroups[$firstLetter], $item);
}

$alphaIndex = array();
$output = '';

foreach ($alphaGroups as $alpha => $alphaGroup) {
    if (count($alphaGroup) == 0) {
        array_push($alphaIndex, $alpha);
    } else {
        array_push($alphaIndex, '<a href="a-to-z-list.html#' . $alpha . '">' . $alpha . '</a>');
        $formattedGroup = '';
        $formattedGroup .= '<h3 id="' . $alpha . '">' . $alpha . '</h3>'; 
        foreach ($alphaGroup as $item) {
            $formattedGroup .= $pdo->getChunk($itemTpl, $item);
            // uncomment the following line to see the item printed out in json format
            //$formattedGroup .= json_encode($item, JSON_PRETTY_PRINT);
        }
        $output .= '<hr>' . $formattedGroup;
    }
}
//return $alphaIndex + this list of resources grouped by letter;
return '<p class="alpha-index">' . implode(' | ', $alphaIndex) . '</p>' . $output;