This fixes#2613 by reloading the form widgets with the modified data after `model.filterFields`. **NOTE**: `$this->processExistingItems()` isn't simply just moved to `prepareVars()` because that messes up the adding new repeater item functionality by repeating the content from the fields for the last item in that group that already exists on the repeater.
* Add support for previewMode in Repeater FormWidget
Refs: #2724, 5f91c45f79
* Add support for previewMode in Repeater FormWidget
Refs: #2724, 5f91c45f79
* Add support for previewMode in Repeater FormWidget
Refs: #2724, 5f91c45f79
* Add support for previewMode in Repeater FormWidget
Refs: #2724, 5f91c45f79
This is useful when a form renders another form inside, specifically the repeater. In these cases the model and data will diverge, and it also provides an opportunity to not apply extension logic to nested form fields.
Fixes#2257