adding form fields on the fly

gistfile1.php

Manipulation a JForm is easy the best place to add fields is to use the preprocessForm function

  protected function preprocessForm(JForm $form, $data, $group = 'content')
	{
		// Add some needed hidden fields
		$fields = array('id','cid');

		foreach ($fields AS $field)
		{
			$element = new SimpleXMLElement('<field></field>');
			$element->addAttribute('name', $field);
			$element->addAttribute('type', 'hidden');
			$element->addAttribute('default', '0');
			$element->addAttribute('readonly', 'true');
			$element->addAttribute('class', 'readonly');
			$form->setField($element);
		}

  	parent::preprocessForm($form, $data, $group);
	}