My app launches successfully without warnings, but as soon as I try to save items via the add to cart controller I get the error with warnings as shown below. I'm not sure what to make of this error at this moment.
I understand that the use of (!) bang is referenced but still, I expect that not to be the problem since I have successfully fetched the instances I need to for executing functions in my controllers. I would appreciate any guidance and understanding if this issue has to do with my code or it's a flutter problem on my machine.
cart_controller with the error showing in line 17
import 'package:get/get.dart';
import 'package:izinto_on_demand/models/popular_specialty_model.dart';
import '../helpers/data/repository/cart_repo.dart';
import '../models/cart_model.dart';
import '../utils/colors.dart';
class CartController extends GetxController {
final CartRepo cartRepo;
CartController({required this.cartRepo});
Map<int, CartModel> _items = {};
Map<int, CartModel> get items => _items;
void addItem(SpecialtyModel specialty, int quantity) {
var totalQuantity = 0;
if (_items.containsKey(specialty.id!)) {
_items.update(specialty.id!, (value) {
// totalQuantity = value.quantity! + quantity;
return CartModel(
id: value.id,
name: value.name,
price: value.price,
time: DateTime.now().toString(),
img: value.img,
material: value.material,
quantity: value.quantity! + quantity,
isExist: true,
provider: value.provider);
});
if (totalQuantity <= 0) {
_items.remove(specialty.id);
}
} else {
if (quantity > 0) {
_items.putIfAbsent(specialty.id!, () {
return CartModel(
id: specialty.id,
name: specialty.name,
price: specialty.price,
time: DateTime.now().toString(),
img: specialty.img,
material: specialty.material,
quantity: quantity,
isExist: true,
provider: specialty.provider);
});
} else {
Get.snackbar('Item count', 'Please select items to add to cart',
backgroundColor: AppColors.mainColor, colorText: Colors.white);
}
}
}
bool existInCart(SpecialtyModel, specialty) {
if (_items.containsKey(specialty.id)) {
return true;
}
return false;
}
int getQuantity(SpecialtyModel specialty) {
var quantity = 0;
if (_items.containsKey(specialty.id!)) {
_items.forEach((key, value) {
if (key == specialty.id) {
quantity = value.quantity!;
}
});
}
return quantity;
}
int get totalItems {
var totalQuantity = 0;
_items.forEach((key, value) {
totalQuantity += value.quantity!;
});
return totalQuantity;
}
}
recommended_specialty_controller with the error referenced again in line 81
import 'package:flutter/material.dart';
import 'package:get/get.dart';
import 'package:izinto_on_demand/controllers/cart_controller.dart';
import 'package:izinto_on_demand/helpers/data/repository/recommended_specialty_repo.dart';
import 'package:izinto_on_demand/models/popular_specialty_model.dart';
import 'package:izinto_on_demand/utils/colors.dart';
class RecommendedSpecialtyController extends GetxController {
final RecommendedSpecialtyRepo recommendedSpecialtyRepo;
RecommendedSpecialtyController({required this.recommendedSpecialtyRepo});
List<dynamic> _recommendedSpecialtyList = [];
List<dynamic> get recommendedSpecialtyList => _recommendedSpecialtyList;
late CartController _cart;
bool _isLoaded = false;
bool get isLoaded => _isLoaded;
int _quantity = 0;
int get quantity => _quantity;
int _inCartItems = 0;
int get inCartItems => _inCartItems + _quantity;
Future<void> getRecommendedSpecialtyList() async {
Response response =
await recommendedSpecialtyRepo.getRecommendedSpecialtyList();
if (response.statusCode == 200) {
print('got specialties');
_recommendedSpecialtyList = [];
_recommendedSpecialtyList
.addAll(Specialty.fromJson(response.body).specialties);
print(_recommendedSpecialtyList);
_isLoaded = true;
update();
} else {
print('this is not working ${response.statusCode}');
}
}
void setQuantity(bool isIncrement) {
if (isIncrement) {
_quantity = checkQuantity(_quantity + 1);
} else {
_quantity = checkQuantity(_quantity - 1);
print('decrement ' + _quantity.toString());
}
update();
}
int checkQuantity(int quantity) {
if ((_inCartItems + quantity) < 0) {
Get.snackbar('Item count', 'You don\'t have items',
backgroundColor: AppColors.mainColor, colorText: Colors.white);
return 0;
} else if ((_inCartItems + quantity) > 20) {
Get.snackbar('Item count', 'Maximum number of items selected',
backgroundColor: AppColors.mainColor, colorText: Colors.white);
return 20;
} else {
return quantity;
}
}
void initSpecialty(SpecialtyModel specialty, CartController cart) {
_quantity = 0;
_inCartItems = 0;
_cart = cart;
var exist = false;
exist = _cart.existInCart(SpecialtyModel, specialty);
//if exist
//get from storage _inCartItems=3
print('exist or not' + exist.toString());
if (exist) {
_inCartItems = _cart.getQuantity(specialty);
}
print('The quantity in the cart is' + _inCartItems.toString());
}
void addItem(SpecialtyModel specialty) {
if (_quantity > 0) {
_cart.addItem(specialty, _quantity);
_quantity = 0;
_cart.items.forEach((key, value) {
print('The id is' +
value.id.toString() +
' The quantity is ' +
value.quantity.toString());
});
} else {
Get.snackbar('Item count', 'You should at least add an item in the cart');
}
update();
}
int get totalItems {
return _cart.totalItems;
}
}
recommended_specialty_detail with the error referenced again in line 212
import 'package:flutter/material.dart';
import 'package:get/get.dart';
import 'package:izinto_on_demand/controllers/cart_controller.dart';
import 'package:izinto_on_demand/controllers/popular_specialty_controller.dart';
import 'package:izinto_on_demand/controllers/recommended_specialty_controller.dart';
import 'package:izinto_on_demand/pages/home/main_specialty_page.dart';
import 'package:izinto_on_demand/utils/dimensions.dart';
import 'package:izinto_on_demand/widgets/App_column.dart';
import 'package:izinto_on_demand/widgets/app_icon.dart';
import 'package:izinto_on_demand/widgets/expandable_text.dart';
import '../../models/popular_specialty_model.dart';
import '../../utils/colors.dart';
import '../../widgets/big_text.dart';
import '../../widgets/icon_and_text_widgets.dart';
import '../../widgets/small_text.dart';
class RecommendedSpecialtyDetail extends StatelessWidget {
int pageId;
RecommendedSpecialtyDetail({Key? key, required this.pageId})
: super(key: key);
@override
Widget build(BuildContext context) {
var specialty = Get.find<RecommendedSpecialtyController>()
.recommendedSpecialtyList[pageId];
Get.find<RecommendedSpecialtyController>()
.initSpecialty(specialty, Get.find<CartController>());
return Scaffold(
backgroundColor: Colors.white,
body: Stack(
children: [
//background image
Positioned(
left: 0,
right: 0,
child: Container(
width: double.maxFinite,
height: Dimensions.popularSpecialtyImgSize,
decoration: BoxDecoration(
image: DecorationImage(
fit: BoxFit.cover,
image: AssetImage(specialty.img),
),
),
),
),
//icon widgets
Positioned(
top: Dimensions.height45,
left: Dimensions.width20,
right: Dimensions.width20,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
GestureDetector(
onTap: () {
Get.to(() => MainSpecialtyPage());
},
child: AppIcon(icon: Icons.arrow_back_ios)),
GetBuilder<RecommendedSpecialtyController>(
builder: (controller) {
return Stack(
children: [
AppIcon(icon: Icons.shopping_cart_outlined),
Get.find<RecommendedSpecialtyController>().totalItems >=
1
? Positioned(
right: 0,
top: 0,
child: AppIcon(
icon: Icons.circle,
size: 20,
iconColor: Colors.transparent,
backgroundColor: AppColors.mainColor,
),
)
: Container(),
Get.find<RecommendedSpecialtyController>().totalItems >=
1
? Positioned(
right: 3,
top: 3,
child: BigText(
text:
Get.find<RecommendedSpecialtyController>()
.totalItems
.toString(),
size: 12,
color: Colors.white,
),
)
: Container()
],
);
},
),
],
),
),
//introduction of specialty services
Positioned(
left: 0,
right: 0,
bottom: 0,
top: Dimensions.popularSpecialtyImgSize - 20,
child: Container(
padding: EdgeInsets.only(
left: Dimensions.width20,
right: Dimensions.width20,
top: Dimensions.height20),
decoration: BoxDecoration(
borderRadius: BorderRadius.only(
topRight: Radius.circular(Dimensions.radius20),
topLeft: Radius.circular(Dimensions.radius20),
),
color: Colors.white,
),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
AppColumn(
text: specialty.name,
),
SizedBox(
height: Dimensions.height20,
),
BigText(text: 'Introduce'),
SizedBox(
height: Dimensions.height20,
),
Expanded(
child: SingleChildScrollView(
child: ExpandableText(text: specialty.introduction),
),
),
],
),
),
),
],
),
bottomNavigationBar: GetBuilder<RecommendedSpecialtyController>(
builder: (recommendedSpecialty) {
return Container(
height: Dimensions.bottomHeightBar,
padding: EdgeInsets.only(
top: Dimensions.height20,
bottom: Dimensions.height20,
left: Dimensions.width20,
right: Dimensions.width20),
decoration: BoxDecoration(
color: AppColors.buttonBackgroundColor,
borderRadius: BorderRadius.only(
topLeft: Radius.circular(Dimensions.radius20 * 2),
topRight: Radius.circular(Dimensions.radius20 * 2),
),
),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Container(
padding: EdgeInsets.only(
top: Dimensions.height20,
bottom: Dimensions.height20,
left: Dimensions.width20,
right: Dimensions.width20),
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(Dimensions.radius20),
color: Colors.white,
),
child: Row(
children: [
GestureDetector(
onTap: () {
recommendedSpecialty.setQuantity(false);
},
child: Icon(
Icons.remove_outlined,
color: AppColors.signColor,
),
),
SizedBox(
width: Dimensions.width15,
),
BigText(
text: recommendedSpecialty.inCartItems.toString(),
),
SizedBox(
width: Dimensions.width15,
),
GestureDetector(
onTap: () {
recommendedSpecialty.setQuantity(true);
},
child: Icon(
Icons.add_outlined,
color: AppColors.signColor,
),
),
],
),
),
Container(
padding: EdgeInsets.only(
top: Dimensions.height20,
bottom: Dimensions.height20,
left: Dimensions.width20,
right: Dimensions.width20),
child: GestureDetector(
onTap: () {
recommendedSpecialty.addItem(specialty);
},
child: BigText(
text: 'R${specialty.price} ' + '| Add to cart',
color: Colors.white,
),
),
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(Dimensions.radius20),
color: AppColors.mainColor,
),
)
],
),
);
},
),
);
}
}
What's in the stack trace
The following _CastError was thrown while handling a gesture: Null check operator used on a null value
When the exception was thrown, this was the stack: #0 CartController.addItem (package:izinto_on_demand/controllers/cart_controller.dart:17:40) #1 RecommendedSpecialtyController.addItem (package:izinto_on_demand/controllers/recommended_specialty_controller.dart:81:13) #2 RecommendedSpecialtyDetail.build.. (package:izinto_on_demand/pages/specialty/recommended_specialty_Detail.dart:212:44) #3 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:198:24) #4 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:608:11) #5 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:296:5)
json map { "Specialties" : [ { "id": 3, "price": "150.00", "createAt": "2022-02-28T13:31:28.497Z", "img": "assets/image/dry42.jpg", "quantity" : [] } ] }
*flutter version C:\Users\CLIENT\Desktop\izinto_on_demand>flutter upgrade Flutter is already up to date on channel stable Flutter 2.10.3 • channel stable • https://github.com/flutter/flutter.git Framework • revision 7e9793dee1 (3 weeks ago) • 2022-03-02 11:23:12 -0600 Engine • revision bd539267b4 Tools • Dart 2.16.1 • DevTools 2.9.2
dependency injection in main.dart
const MyApp({Key? key}) : super(key: key);
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
Get.find<RecommendedSpecialtyController>().getRecommendedSpecialtyList();
Get.find<PopularSpecialtyController>().getPopularSpecialtyList();
Get.lazyPut(() => CartController(cartRepo: Get.find()));
return GetMaterialApp(
debugShowCheckedModeBanner: false,
specialty model
late List<SpecialtyModel> _specialties;
List<SpecialtyModel> get specialties => _specialties;
Specialty({required specialties}) {
this._specialties = specialties;
}
Specialty.fromJson(Map<String, dynamic> json) {
if (json['Specialties'] != null) {
_specialties = <SpecialtyModel>[];
json['Specialties'].forEach((v) {
_specialties.add(SpecialtyModel.fromJson(v));
});
}
}
}
class SpecialtyModel {
int? id;
String? name;
String? introduction;
String? price;
String? createAt;
String? img;
List<double>? location;
String? provider;
String? material;
SpecialtyModel(
{this.id,
this.name,
this.introduction,
this.price,
this.createAt,
this.img,
this.location,
this.material,
this.provider});
SpecialtyModel.fromJson(Map<String, dynamic> json) {
id = json['id'];
name = json['name'];
introduction = json['introduction'];
price = json['price'];
createAt = json['createAt'];
img = json['img'];
material = json['material'];
location = json['location'].cast<double>();
provider = json['provider'];
}
}
