<?php

include "bootstrap.php";
$doc = new SolrDocument();
$second_doc = new SolrDocument();
$doc->addField('id', 1123);
$doc->features = "PHP Client Side";
$doc->features = "Fast development cycles";
$doc['cat'] = 'Software';
$doc['cat'] = 'Custom Search';
$doc->cat = 'Information Technology';
$second_doc->addField('cat', 'Lucene Search');
$second_doc->merge($doc, true);
print_r($second_doc->toArray());
<?php

include "bootstrap.php";
$doc = new SolrDocument();
$doc->addField('id', 1123);
$doc->features = "PHP Client Side";
$doc->features = "Fast development cycles";
$doc['cat'] = 'Software';
$doc['cat'] = 'Custom Search';
$doc->cat = 'Information Technology';
print_r($doc->toArray());