Update a dataset without reloading index

Hello all!

Again a special question about a flow only application.
Following scenario:

I have a “overview page” (feeded by indexAction of a custom model).
This overview ist structured like a TreeView. Branches of this TreeView
contain depending instances of other models and so on. Branch depth is variable from one to abaout five.

User can expand several sub-branches by clicking according icons.

Now my problem: if one edit on a sub-model instance, this is done in an modal. Form data there are filled by an AJAX call to a controller action.

Problem first part: how to process data, if an error occours on saving?
Without any special handling, flash messages and formdata are shown now unformatted in DOM root. How can I redirect the output to the modal?

Problem second part: if there are no erros on saving, index is reloaded into inital state. All “opened” sub-branches are closed. For the user very annoying…

I’ve tried to use $this->forward('index') in controllers updateAction. but this does not work.

Have someone some ideas or hints to solve theese problems.

The view is a TemplateView; can I use a JsonView here?

Flow Version is 8.3

Bit late answer but as I am here, this very much depends on your frontend, but for an AJAX request the page shouldn’t reload when it’s done? Also the errors etc. should return within the AJAX response. And you can always opt to not output flash messages and form errors (or output them at differnet places).