Can't build new widget on pressing button at run time in FormBuilder - flutter

Question

I am trying to build a new widget every time a button is pressed.
I am using object of Global key to change the current state of Form as other local keys doesn't provide me the capability to change the state of FormBuilder
final _formKey = GlobalKey<FormBuilderState>();
Problem is when I try to create object of GlobalKey(_formKey) under listTile widget that I 'm trying to build on runtime, form builderr text fields don't work i.e appear and disappear instantly! But when create _formKey oustside the listTile widget under stateful widget, many other errors appears
i.e setState() called after dispose(), Global key used for multiple widgets etc.
Should I use here local keys i.e value,object or unique key? But they aren't providing me to change the current state of form builder!
Check my code:
class _addMenuState extends State<addMenu> {
var _price = TextEditingController();
var _itemName = TextEditingController();
var _desc = TextEditingController();
File _image;
String itemImageUrl;
List<menu> items = [];
final _formKey = GlobalKey<FormBuilderState>();
Future getImageFromGallery() async {
var image = await ImagePicker.pickImage(source: ImageSource.gallery);
setState(() {
_image = image;
print('Image Path $_image');
});
}
Future getImageFromCamera() async {
var image = await ImagePicker.pickImage(source: ImageSource.camera);
setState(() {
_image = image;
print('Image Path $_image');
});
}
Future uploadItemOfShop(BuildContext context) async {
FirebaseStorage storage = FirebaseStorage.instance;
Reference ref = storage.ref().child("${this.widget.rr.name}'s ${_itemName.text} Price ${_price.text}" + DateTime.now().toString());
if(_image.toString()==''){
Flushbar(
title: "Menu Item Image is empty",
message: "Please Add some Image first",
backgroundColor: Colors.red,
boxShadows: [BoxShadow(color: Colors.red[800], offset: Offset(0.0, 2.0), blurRadius: 3.0,)],
duration: Duration(seconds: 3),
)..show(context);
}else{
UploadTask uploadTask = ref.putFile(_image);
uploadTask.then((res) async {
itemImageUrl = await res.ref.getDownloadURL();
});
}
/* setState(() {
print("Logo uploaded");
Scaffold.of(context).showSnackBar(SnackBar(
content: Text('Your Restaurnat Logo has Uploaded'),
duration: Duration(seconds: 3),
));
});*/
}
Widget Divido() {
return Divider(
thickness: 5,
color: Colors.black45,
height: 2,
);
}
Widget listTile(int i) {
final _formKey = GlobalKey<FormBuilderState>();
return SingleChildScrollView(
child: ListTile(
title: //Code not needed here for this question as I haven't used key in it
subtitle: FormBuilder(
key: _formKey,
child: Column(
children: [
FormBuilderTextField(
controller: _itemName,
keyboardType: TextInputType.text,
name: 'item_name',
decoration: InputDecoration(labelText: 'Enter Item name'),
validator: FormBuilderValidators.compose([
FormBuilderValidators.required(context),
]),
),
FormBuilderTextField(
controller: _price,
name: 'price',
keyboardType: TextInputType.number,
decoration: InputDecoration(labelText: 'Enter Price'),
validator: FormBuilderValidators.compose([
FormBuilderValidators.required(context),
]),
),
FormBuilderTextField(
maxLength: 150,
controller: _desc,
keyboardType: TextInputType.multiline,
maxLines: null,
name: 'desc',
decoration: InputDecoration(
labelText: 'Description',
),
validator: FormBuilderValidators.compose(
[
FormBuilderValidators.required(context),
],
),
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: [
RaisedButton(
child: Text(
"Save",
style: TextStyle(color: Colors.white, fontSize: 16),
),
color: Colors.red,
onPressed: () {
debugPrint("null");
menu item = menu(
_itemName.text, _price.text, _desc.text, itemImageUrl);
items.add(item);
setState(() {
_count = _count + 1;
});
},
),
RaisedButton(
child: Text(
"Reset",
style: TextStyle(color: Colors.white, fontSize: 16),
),
color: Colors.grey,
onPressed: () {
_formKey.currentState.reset();
},
)
],
),
Divido()
],
),
),
selectedTileColor: Colors.red.shade300,
),
);
}
int _count = 1;
bool _showAnotherWidget = false;
#override
Widget build(BuildContext context) {
List<Widget> children = List.generate(_count, (int i) => listTile(i));
return Scaffold(
appBar: AppBar(
title: Text("Add Menu for ${this.widget.rr.name} Shop"),
),
body: SingleChildScrollView(
child: Container(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: children
),
),
)
);
}
}