Modx Resource List as checkbox for users - checkbox

Question

Please help, I am stuck with Modx Revo tv input type options.
What I want to achieve is have a checkbox type tv, that displays the resources of a particular parent as checkbox items. So when user checks an item or two, they will be outputted as comma separated values.
Than I will put my tv in a getresources call on the template and it will output some information form the checked resources.
So how do I convert resource list into checkbox options?
The documentation on this is very ambiguous.

Answer 1

Accomplishing this requires some work, but it is not very difficult.
First, create a new Template Variable. Name it whatever you want, for example list_children. Then go to Input Options tab and set Input Type to Checkbox and under Input Option Values enter the following:
#eval return $modx->runSnippet('list_children');
Go to the Output Options tab and select Delimiter in the Output Type dropdown. In the Delimiter textbox write a single comma ,. Apply the Template Variable to your Template of choice and save.
New, create a new Snippet. Name this list_children, or whatever you changed the eval expression to call.
In this snippet, fill in the following:
<?php
$c = $modx->newQuery('modResource');
$c->where(array(
'parent' => 2, // Id to fetch children from
'published' => 1, // Remove this line if you also want to include unpublished resources
'deleted' => 0 // Remove this line if you also want resources that are marked for deletion
));
$c->sortby('menuindex', 'ASC');
$collection = $modx->getCollection('modResource', $c);
$output = array();
foreach ($collection as $v) {
$output[] = $v->get('pagetitle') . '==' . $v->get('id');
}
return implode('||', $output);

Answer 2

I found an alternative way.
Make TV with Input Type Checkbox.
Put #SELECT pagetitle, id FROM modx_site_content WHERE parent=123
!Attn. pay attention on modx_site_content, it needs to reflect MySQL db prefix, which in this case is modx, change 123 to respective parent id.
Change TV output type to Delimiter and coma (,) as delimiter.
Set TV access to respective templates.
Now you can select any or many children of a parent resource which will output their ids as TV output. E.g. let's say our parent 123 had children 33, 34 and 35. In Template variable sections of the resource using the template with access to tv, you will find a checkbox list with children titles. Selecting one or more, e.g. 33 and 35 will output "33,35" in the tv used in chunk.
I found the solution in Modx forums. Lost the link unfortunately.