TreeDropdownField doesn't work with Widget::getCMSFields()

[MattyBalaam]

No description provided.

[spierala]

same here. i get this error:
Fatal error: Call to a member function FormAction() on a non-object in FormField.php on line 139

[MattyBalaam]

Hi, if you see here you can see more details about this issue: #20

The best solution I have come up with so far is on this thread: http://www.silverstripe.org/widgets-2/show/20865

[Bob-Plastyk]

It would be great to have TreeDropdownField for Widgets.

[christopherdarling]

There's a good extension you can use to manage widgets via a GridField in SS3, so you can use UploadField's and TreeDropdownField's etc too - https://github.com/g4b0/silverstripe-widget-pages-extension

[mlewis-everley]

I have done some digging into this issue, it appears that TreeDropdownField is unaware of what form it is being added to. Widget::getCMSFields() doesn't seem to use TreeDropdownField::setForm() correctly and so this error is raised.

You can manually set the form in your getCMSFields function, but I am not sure how to get the current Form from the CMS (Controller::curr()->EditForm() causes a different error).

I have kind of gotten stuck at this point, I guess the best solution would be for Widgets to setForm correctly on fields such as TreeDropdownField, UploadField, etc, not really sure how though.

[mlewis-everley]

I have just done a little more digging, I think the issue can be tracked down to something inside this loop:

https://github.com/silverstripe/silverstripe-widgets/blob/master/src/Model/Widget.php#L202

If I have time later today, I may try and have a play around, see if I can work our what is causing it...