The FocusNode that is used for the text field.
The main purpose of this parameter is to allow the use of a separate text field located in another part of the widget tree instead of the text field built by fieldViewBuilder. For example, it may be desirable to place the text field in the AppBar and the options below in the main body.
When following this pattern, fieldViewBuilder can be omitted, so that a text field is not drawn where it would normally be. A separate text field can be created elsewhere, and a FocusNode and TextEditingController can be passed both to that text field and to RawAutocomplete.
To create a local project with this code sample, run:
flutter create --sample=widgets.RawAutocomplete.focusNode.1 mysample
If this parameter is not null, then textEditingController must also be not null.
final FocusNode? focusNode;