Moodle Form processing array on submit - php

Question

I'm working on processing data returned from a form but because I've had to manually assign ids to the select dropdowns (so that I can attach a help button to the headings) I can't find an example to work from.
The array being returned looks like this:
[10]=>
string(1) "0"
[11]=>
string(1) "0"
[12]=>
string(1) "0"
[20]=>
string(1) "0"
[21]=>
string(1) "0"
[22]=>
string(1) "0"
["comments"]=>
string(0) ""
["submitbutton"]=>
string(12) "Save changes"
What I need to do is group all that start with a unique number (i.e. 1,2...) and ignore the comments and submitbutton elements.
In other words, I want it to look like this:
id = 1
criteria0 = 0
criteria1 = 0
criteria2 = 0
id = 2
criteria0 = 0
criteria1 = 0
criteria2 = 0

Answer 1

Think I would just use a delimiter, eg:
In the form
foreach (array(1,2) as $id) {
foreach (array(1,2,3) as $criteria) {
$key = $id . '_' . $criteria;
$options[$key] = "Your description for id $id, criteria $criteria";
}
}
$attributes = array('multiple' => 'multiple', 'size' => 10);
$form->addElement('select', 'criteria', get_string('criteria', 'component'), $options, $attributes);
Then in the results
$formdata = $mform->get_data();
...
$results = array();
foreach ($formdata->criteria[$key] as $key => $value) {
list($id, $criteria) = explode('_', $key);
$results[$id][$criteria] = $value;
}
Also for reference, Moodle has a selectgroups field type. You will still need to use a unique key but you can group the options.
foreach (array(1,2) as $groupid) {
foreach (array(1,2,3) as $criteria) {
$key = $groupid . '_' . $criteria;
// Use a group.
$options[$groupid][$key] = "Your description for id $groupid, criteria $criteria";
}
}
$attributes = array('multiple' => 'multiple', 'size' => 10);
// Use selectgroups.
$form->addElement('selectgroups', 'criteria', get_string('criteria', 'component'), $options, $attributes);