Cannot redeclare class tl_form_field

[freeyland]

Hi,

I want to use the functionality of the form module inside my module. The problem is that i can not extend the class tl_form as my forms need to be attached to an other element.
I tried to adapt the DCA from tl_form with array_insert. This is working but the original tl_form is then not working anymore as it is outputting an error that it can not find tl_ff_tasks when using the form module
This is the reason why I did the following:

$this->loadLanguageFile('tl_form');
include(TL_ROOT.'/system/modules/backend/dca/tl_form.php');

$GLOBALS['TL_DCA']['tl_ff_form']=$GLOBALS['TL_DCA']['tl_form'];

array_insert($GLOBALS['TL_DCA']['tl_ff_form']['config']['ptable'], 1, 'tl_ff_tasks');  <== other element
array_insert($GLOBALS['TL_DCA']['tl_ff_form']['config']['ctable'], 1, array('tl_ff_form_field')
);
...... Some extra fields

class tl_ff_form extends Backend
{

	/**
	 * Import the back end user object
	 */
	public function __construct()
	{
		parent::__construct();
		$this->import('BackendUser', 'User');
	}

	public function deleteFormButton($row, $href, $label, $title, $icon, $attributes)
	{
		return ($this->User->isAdmin || $this->User->hasAccess('delete', 'flexiform')) ? ''.$this->generateImage($icon, $label).' ' : $this->generateImage(preg_replace('/\.gif$/i', '_.gif', $icon)).' ';
	}

}

Is this the correct way?
+
I have the following issue: When i try to delete a tl_ff_form I get the following error:
Fatal error: Cannot redeclare class tl_form_field in /Users/freeyland/Sites/bureauguide/system/modules/backend/dca/tl_form_field.php on line 627
Why does it keep referencing to tl_form_field?

[ga.n]

if you are using Contao 2.10.x try to empty the cache (Maintenance under System)

I've read about some issues with this new functionality

[freeyland]

Thanx, but already tried

[ga.n]

replace

include(TL_ROOT.'/system/modules/backend/dca/tl_form.php');

with

$this->loadDataContainer('tl_form');

[freeyland]

Thanx!!!! Logic, I was loading the class twice.