How to add additional **custom** fields to use by another field

BTW what I've done until now, is call the other handler's query logic statically. (Long live PHP's scope structure!!)

class views_handler_field_node_registration_available_slots extends views_handler_field_entity {
  function query() {
    // PHP's very unnatural scoping allows the other handler to alter this handler's $this
    views_handler_field_node_registration_used_slots::query();
  }
}

Problem is this leads to a "call-time pass-by-reference is deprecated" warning somewhere. I can't pinpoint why or where, but this is the reason.

I'd rather just 'force load' the other field handler's field.

I don't get it... Is the language part necessary??

If I add a field handler in ->init, that handler doesn't exist anymore in ->query, so it's not saved or not used or something... It must exist before ->query is called though. ->init sounds good in theory, but the query isn't altered.

My init function:

	function init(&$view, &$options) {
		parent::init(&$view, &$options);
		$this->view->init_style();

		$this->additional_fields['nid'] = 'nid';

		$field_handlers = &$this->view->display_handler->handlers['field'];

		$handler_name = 'registration_used_slots';
		$handler = views_get_handler($this->table, $handler_name, 'field');
		$handler_options = array(
			'id' => $handler_name,
			'table' => $this->table,
			'field' => $handler_name,
			'label' => $handler_name,
		) + $options;
		$handler->main_field = $options['id'];
		$handler->init($view, $handler_options);
		$field_handlers[$handler_name] = $handler;
	}

Field 'registration_used_slots' isn't added.

There's no field property in $view. Or in a handler or a display...

I've added the field to the display's fields list. (Using display_handler->get_option and display_handler->set_option).

That does the trick. (Initing and attaching the handler etc is still required.)

Not as perfect as I'd hoped. Doing it like this (adding the field to the fields list programmatically) adds the field to the actual field list, which means it's clickable. The field doesn't really exist there, though, so you can't delete or edit it. Editing it opens a blank overlay.

Adding the field explicitly adds it the 'right' way and makes it editable.

This is acceptable for my purposes, but I would love it if this were a feature and not a hack =) Sounds like a sister for ->add_additional_fields.

My ->init:

	function init(&$view, &$options) {
		parent::init(&$view, &$options);
		$this->view->init_style();

		$this->additional_fields['nid'] = 'nid';

		$handler_name = 'registration_used_slots';
		$field_handlers = &$this->view->display_handler->handlers['field'];

		$fields = $this->view->display_handler->get_option('fields');
		if (!isset($fields[$handler_name])) {
			// Create, init and attach handler.
			$handler = views_get_handler($this->table, $handler_name, 'field');
			$handler_options = array(
				'id' => $handler_name,
				'table' => $this->table,
				'field' => $handler_name,
				'label' => 'AUTOMATIC',
				'exclude' => TRUE,
			);
			$handler->main_field = $options['id'];
			$handler->init($view, $handler_options);
			$field_handlers[$handler_name] = $handler;

			// Create and attach fake field.
			$fields[$handler_name] = $handler_options;
			$this->view->display_handler->set_option('fields', $fields);
		}
	}

Thanks @dawehner and @merlinofchaos.

Yup. That does exactly the same, but slightly less.

I'd still like to see it as a feature: add temporary custom fields to be reused by other fields. Like add_additional_fields, but slightly more complicated.

Any takers? =)