Conditional statement not working correctly in Dart - flutter

Question

By clicking on save button of the form, user either updates and existing item or add a new one. For that, in _saveForm() method, I have implemented the following if statement, but it doesn't work properly. It just updates the already-existing item and when it comes to add a new one, It does not. What is the problem?
Future<void> _saveForm() async {
final isValid = _form.currentState!.validate();
if (!isValid) {
return;
}
_form.currentState!.save();
setState(() {
_isLoading = true;
});
if (_editedItem.id != null) {
await Provider.of<Items>(context, listen: false)
.updateItem(_editedItem.id.toString(), _editedItem);
setState(() {
_isLoading = false;
});
Navigator.of(context).pop();
} else {
try {
await Provider.of<Items>(context, listen: false).addItem(_editedItem);
} catch (error) {
await showDialog(
context: context,
builder: (ctx) => AlertDialog(
title: const Text('An error occurred!'),
content: const Text('Something went wrong.'),
actions: <Widget>[
FlatButton(
child: Text('Okay'),
onPressed: () {
Navigator.of(ctx).pop();
},
)
],
),
);
}
}
setState(() {
_isLoading = false;
});
Navigator.of(context).pop();
}
Followings are the methods called inside _saveForm() function:
Future<void> updateItem(String id, Item newItem) async {
final itemIndex = _items.indexWhere((item) => item.id == id);
if (itemIndex >= 0) {
final url = 'https://shaparak-732ff.firebaseio.com/items/$id.json';
await http.patch(Uri.parse(url),
body: json.encode({
'title': newItem.title,
'content': newItem.content,
'author': newItem.author,
'category': newItem.category,
'startColor': newItem.startColor,
'endColor': newItem.endColor,
}));
_items[itemIndex] = newItem;
notifyListeners();
} else {
print('...');
}
}
And the method that does not function:
Future<void> addItem(Item item) {
const url = 'https://shaparak-732ff.firebaseio.com/items.json';
return http
.post(
Uri.parse(url),
body: json.encode({
'title': item.title,
'content': item.content,
'author': item.author,
'category': item.category,
'startColor': item.startColor,
'endColor': item.endColor,
}),
)
.then((response) {
final newItem = Item(
title: item.title,
content: item.content,
author: item.author,
category: item.category,
startColor: item.startColor,
endColor: item.endColor,
id: json.decode(response.body)['name'],
);
_items.add(newItem);
// _items.insert(0, newProduct); // at the start of the list
notifyListeners();
});
}

Answer 1

I think you don't add your product id, you will follow this code .....
Future<void> addItem(Item item) {
const url = 'https://shaparak-732ff.firebaseio.com/items.json';
return http
.post(
Uri.parse(url),
body: json.encode({
'id': item.id,
'title': item.title,
'content': item.content,
'author': item.author,
'category': item.category,
'startColor': item.startColor,
'endColor': item.endColor,
}),
)
.then((response) {
final newItem = Item(
id: json.decode(response.body)['name'],
title: item.title,
content: item.content,
author: item.author,
category: item.category,
startColor: item.startColor,
endColor: item.endColor
);
_items.insert(0, newItem);
notifyListeners();
});
}

Answer 2

Hey basically your problem looks like it might be because id can never be null. So instead of
if (_editedItem.id != null) {
await Provider.of<Items>(context, listen: false)
.updateItem(_editedItem.id.toString(), _editedItem);
setState(() {
_isLoading = false;
});
try making it say
if (_editedItem.id != '') {
await Provider.of<Items>(context, listen: false)
.updateItem(_editedItem.id.toString(), _editedItem);
setState(() {
_isLoading = false;
});