Can't send post requests from Flutter to Firebase Realtime Database - firebase

Question

i am a flutter beginner and i am getting the "Flutter & Dart - The Complete Guide [2022 Edition]" course at Udemy (if you know the course i am at Section 10, Lesson 242 "Sending POST Requests". This is my first time using Firebase and a database and i stuck at this problem for quite some time now. We built a basic shop app at previous sections at course and now we are supposed to send a Post request to our Firebase realtime database when we add a new product to our app. We supposed to add some basic information to our database about product. When i try to add a new product, nothing happens, no data at my database and no new product at my app (adding product to app happens in same function right after sending Post request). There is no error at my terminal only one line below.
I/flutter (11699): ...
I was able to add products to app before adding http package and writing the post request codes from last lesson. These are my debug, database rules, and the function that sends post request.
void addProduct(Product product) {
final url = Uri.parse(
'https://flutter-update-ca55a-default-rtdb.firebaseio.com/products.json');
http.post(
url,
body: json.encode({
'title': product.title,
'description': product.description,
'imageUrl': product.imageUrl,
'price': product.price,
'isFavorite': product.isFavorite,
}),
);
final newProduct = Product(
id: DateTime.now().toString(),
title: product.title,
description: product.description,
price: product.price,
imageUrl: product.imageUrl);
_items.add(newProduct);
notifyListeners();
}
I tried course constructors example codes and it didn't work. Then i tried disabling my firewall, changing my database rules to as seen in my question, still same problem. I don't even know if my code is communicating with firebase or not.
Edit:
Sometimes i get the latest text at my Terminal as well, adding a screenshot below:
Click to see Terminal SS
Edit 2 : So i created an empty project to see if my computer is communicating with firebase at all and it worked, i added information to my database from a single screen app. I afraid i have a logical error in my Shop App (most likely at the screen i use addProduct function) so i am posting the code if you see the mistake please warn me. This is edit-product-screen, where i use addProduct function via provider.
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import '../providers/product.dart';
import '../providers/product_provider.dart';
class EditProductScreen extends StatefulWidget {
static const String routeName = '/edit-product-screen';
#override
State<EditProductScreen> createState() => _EditProductScreenState();
}
class _EditProductScreenState extends State<EditProductScreen> {
//final _priceFocusNode = FocusNode();
//final _descriptionFocusNode = FocusNode();
final _imageUrlController = TextEditingController();
//final _imageUrlFocusNode = FocusNode();
final _form = GlobalKey<FormState>();
var _editedProduct =
Product(id: '', title: '', description: '', price: 0, imageUrl: '');
var _isInit = true;
var _isloading = false;
var _initValues = {
'title': '',
'description': '',
'price': '',
'imageUrl': '',
};
#override
void initState() {
//_imageUrlFocusNode.addListener(_updateImageUrl);
super.initState();
}
#override
void didChangeDependencies() {
if (_isInit) {
final String? productId =
ModalRoute.of(context)!.settings.arguments as String?;
if (productId != null) {
_editedProduct = Provider.of<ProductProvider>(context, listen: false)
.findbyID(productId);
_initValues = {
'title': _editedProduct.title,
'description': _editedProduct.description,
'price': _editedProduct.price.toString(),
// 'imageUrl': _editedProduct.imageUrl,
'imageUrl': '',
};
_imageUrlController.text = _editedProduct.imageUrl;
}
}
_isInit = false;
super.didChangeDependencies();
}
// #override
// void dispose() {
// _imageUrlFocusNode.removeListener(_updateImageUrl);
// _priceFocusNode.dispose();
// _descriptionFocusNode.dispose();
// _imageUrlController.dispose();
// _imageUrlFocusNode.dispose();
// super.dispose();
// }
void _updateImageUrl() {
// if (!_imageUrlFocusNode.hasFocus) {
// if ((!_imageUrlController.text.startsWith('http') &&
// !_imageUrlController.text.startsWith('https')) ||
// (!_imageUrlController.text.endsWith('.png') &&
// !_imageUrlController.text.endsWith('.jpg') &&
// !_imageUrlController.text.endsWith('.jpeg'))) {
// return;
// }
setState(() {});
//}
}
void _saveForm() {
final isValid = _form.currentState!.validate();
if (!isValid) {
return;
}
_form.currentState!.save();
setState(() {
_isloading = true;
});
if (_editedProduct.id != null) {
//var olan bir product editleniyor
Provider.of<ProductProvider>(context, listen: false)
.updateProduct(_editedProduct.id, _editedProduct);
setState(() {
_isloading = false;
});
Navigator.of(context).pop();
} else {
//yeni bir product oluşturuluyor.
Provider.of<ProductProvider>(context, listen: false)
.addProduct(_editedProduct)
.catchError((error) {
return showDialog<Null>(
context: context,
builder: (ctx) => AlertDialog(
title: Text('An Error Occured'),
content: Text(error.toString()),
actions: [
FlatButton(
onPressed: () {
Navigator.of(ctx).pop();
},
child: Text('Okay'))
],
),
);
}).then((_) {
setState(() {
_isloading = false;
});
Navigator.of(context).pop();
});
}
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Edit Products'),
actions: [
IconButton(
onPressed: _saveForm,
icon: Icon(Icons.save),
),
],
),
body: _isloading
? Center(
child: CircularProgressIndicator(),
)
: Padding(
padding: const EdgeInsets.all(16.0),
child: Form(
key: _form,
child: ListView(
children: [
TextFormField(
initialValue: _initValues['title'],
decoration: InputDecoration(labelText: 'Title'),
validator: (value) {
if (value!.isEmpty) {
return 'Please enter a title';
}
return null;
},
textInputAction: TextInputAction.next,
// onFieldSubmitted: (_) {
// FocusScope.of(context).requestFocus(_priceFocusNode);
// },
onSaved: (value) {
_editedProduct = Product(
title: value as String,
price: _editedProduct.price,
description: _editedProduct.description,
imageUrl: _editedProduct.imageUrl,
id: _editedProduct.id,
isFavorite: _editedProduct.isFavorite,
);
},
),
TextFormField(
initialValue: _initValues['price'],
decoration: InputDecoration(labelText: 'Price'),
textInputAction: TextInputAction.next,
keyboardType: TextInputType.number,
//focusNode: _priceFocusNode,
// onFieldSubmitted: (_) {
// FocusScope.of(context).requestFocus(_descriptionFocusNode);
// },
validator: (value) {
if (value!.isEmpty) {
return 'Please enter a price';
}
if (double.tryParse(value) == null) {
return 'Please enter a valid number';
}
if (double.parse(value) <= 0) {
return 'Plase enter a number greater than zero';
}
return null;
},
onSaved: (value) {
_editedProduct = Product(
title: _editedProduct.title,
price: double.parse(value as String),
description: _editedProduct.description,
imageUrl: _editedProduct.imageUrl,
id: _editedProduct.id,
isFavorite: _editedProduct.isFavorite,
);
},
),
TextFormField(
initialValue: _initValues['description'],
decoration: InputDecoration(labelText: 'Description'),
maxLines: 3,
validator: (value) {
if (value!.isEmpty) {
return 'Please enter a description';
}
if (value.length < 10) {
return 'Your description must be longer then 10 characters';
}
return null;
},
textInputAction: TextInputAction.next,
//focusNode: _descriptionFocusNode,
keyboardType: TextInputType.multiline,
onSaved: (value) {
_editedProduct = Product(
title: _editedProduct.title,
price: _editedProduct.price,
description: value as String,
imageUrl: _editedProduct.imageUrl,
id: _editedProduct.id,
isFavorite: _editedProduct.isFavorite,
);
},
),
Row(
crossAxisAlignment: CrossAxisAlignment.end,
children: <Widget>[
Container(
width: 100,
height: 100,
margin: EdgeInsets.only(top: 8, right: 10),
decoration: BoxDecoration(
border: Border.all(width: 1, color: Colors.grey),
),
child: _imageUrlController.text.isEmpty
? Text('Enter a URL')
: FittedBox(
child: Image.network(
_imageUrlController.text,
fit: BoxFit.cover,
),
),
),
Expanded(
child: TextFormField(
decoration: InputDecoration(labelText: 'Image URL'),
validator: (value) {
if (value!.isEmpty) {
return 'Please enter a image url';
}
if (!value.startsWith('http') &&
!value.startsWith('https')) {
return 'Please enter a valid image url';
}
return null;
},
keyboardType: TextInputType.url,
textInputAction: TextInputAction.done,
controller: _imageUrlController,
//focusNode: _imageUrlFocusNode,
onFieldSubmitted: (_) {
_saveForm();
},
onSaved: (value) {
_editedProduct = Product(
title: _editedProduct.title,
price: _editedProduct.price,
description: _editedProduct.description,
imageUrl: value as String,
id: _editedProduct.id,
isFavorite: _editedProduct.isFavorite,
);
},
),
),
],
)
],
),
),
),
);
}
}
And this is the latest version of addProduct function
Future<void> addProduct(Product product) async {
final url = Uri.parse(
'https://flutter-update-ca55a-default-rtdb.firebaseio.com/products2.json');
try {
final response = await http.post(
url,
body: json.encode({
'title': product.title,
'description': product.description,
'imageUrl': product.imageUrl,
'price': product.price,
'isFavorite': product.isFavorite,
}),
);
print(json.decode(response.body));
final newProduct = Product(
id: DateTime.now().toString(),
title: product.title,
description: product.description,
price: product.price,
imageUrl: product.imageUrl);
_items.add(newProduct);
notifyListeners();
} catch (error) {
print(error);
throw error;
}
}

Answer 1

I'm thinking you're missing to implement await. Could you try to add await in the beginning http.post after trying to change your method Future then it going to work.
Future<Product> addProduct(Product product) async{
final url = Uri.parse(
'https://flutter-update-ca55a-default-rtdb.firebaseio.com/products.json');
await http.post(
url,
body: json.encode({
'title': product.title,
'description': product.description,
'imageUrl': product.imageUrl,
'price': product.price,
'isFavorite': product.isFavorite,
}),
);
And lastly, you should be use json to dart side for parsing and try to implement json encode to your model with factory methods. ( I've added my first post to your backend, please don't forget to change write rules for everyone)
If you want to learn more detail, please look at dart.pad
samples:
https://dartpad.dev/?id=c04e9842d98ac871988973df025c097e

Answer 2

Maybe this is late answer, but this problem has happened to me also,
if (_editedProduct.id != null) - in this line you are making a mistake, this should be: if (_editedProduct.id != '')
I hope it helps.

Answer 3

Actually i had the same problem, it is a not logical error as it might sound, I only created a new project with a new realtime data base with a different location than my vpn for instance my vpn was set to be US so i set realtime location on Belgium. I hope it works out for u as well.