Unable to retrieve fetch ID data from API. How to fix? - flutter

Question

I want to fetch details of a product by retrieving its ID and by accessing its Id to load the details needed but I keep getting an error that I dont quite understand?
here is my provider data:
class AddCar {
int id;
String name;
String city;
String country;
String currencyT;
double price;
String date;
int sponsNum;
String category;
String company;
String model;
String year;
String engine;
double distanceCovered;
String transmission;
String oilT;
String outColor;
String inColor;
String description;
File image;
PlaceLocation location;
bool isFavorite;
AddCar({
this.id,
this.name,
this.city,
this.country,
this.currencyT,
this.price,
this.date,
this.sponsNum,
this.category,
this.company,
this.model,
this.year,
this.engine,
this.distanceCovered,
this.transmission,
this.oilT,
this.outColor,
this.inColor,
this.description,
this.image,
this.location,
this.isFavorite = false,
});
}
class PlaceLocation {
final double latitude;
final double longitude;
final String address;
const PlaceLocation({
this.address,
this.latitude,
this.longitude,
});
}
Here is how im fetching the data (i have a link to a custome ID that im clicking on to lead to that product):
Future<void> fetchAndSetCarDetails() async {
const url = 'customLink/Detail?Id=204';
final response = await http.get(url);
final extractedData = json.decode(response.body) as Map<String, dynamic>;
List<AddCar> loadedCars = [];
extractedData.forEach((carId, carData) {
loadedCars.add(AddCar(
id: int.parse(carId),
name: carData['adTitle'],
sponsNum: carData['adNumber'],
price: carData['adPrice'],
date: carData['adDate'],
model: carData['brandModel'],
year: carData['modelYear'],
distanceCovered: carData['kilometer'],
transmission: carData['gearType'],
oilT: carData['fuelType'],
location: carData['adLocation'][PlaceLocation(
address: carData['adAddress'],
latitude: carData['lath'],
longitude: carData['lang'],
)],
description: carData['adDetails'],
country: carData['country'],
city: carData['cityName'],
category: carData['category'],
company: carData['brand'],
engine: carData['cylinder'],
outColor: carData['exteriorColor'],
inColor: carData['interiorColor'],
));
});
_cars = loadedCars;
print(response.body);
notifyListeners();
}
Here is the print data I get:
I/flutter (13626): {"id":204,"adTitle":null,"adDate":"2019-11-07T11:52:40.0156875","adPrice":25.0,"adNumber":195,"adAddress":"AdAddressssssss","adLocation":{"lath":"40.959028921030104","lang":" 30.992774628906318"},"adDetails":null,"country":227,"cityName":"Stockholm","category":"car child 1","categoryId":7,"brand":"mercedes","brandId":1,"brandModelId":6,"brandModel":"M300","cylinder":"6C","kilometer":300.0,"modelYear":"2010","fuelType":"benz","gearType":"automatic","exteriorColor":"red","interiorColor":"yellow","carType":1,"image":[],"isFavorite":false,
Here is the error I get when I click on the product to access its details:
E/flutter (13626): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: FormatException: Invalid radix-10 number (at character 1)
E/flutter (13626): id
E/flutter (13626): ^
E/flutter (13626):
E/flutter (13626): #0 int._throwFormatException (dart:core-patch/integers_patch.dart:131:5)
E/flutter (13626): #1 int._parseRadix (dart:core-patch/integers_patch.dart:142:16)
E/flutter (13626): #2 int._parse (dart:core-patch/integers_patch.dart:100:12)
E/flutter (13626): #3 int.parse (dart:core-patch/integers_patch.dart:63:12)
E/flutter (13626): #4 Cars.fetchAndSetCarDetails.<anonymous closure>
package:flutter_app/providers/car_provider.dart:88
E/flutter (13626): #5 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
E/flutter (13626): #6 Cars.fetchAndSetCarDetails
package:flutter_app/providers/car_provider.dart:86
E/flutter (13626): <asynchronous suspension>
E/flutter (13626): #7 _MyCarDetailsState.initState.<anonymous closure>
package:flutter_app/details/car_details.dart:23
E/flutter (13626): #8 _rootRunUnary (dart:async/zone.dart:1132:38)
E/flutter (13626): #9 _CustomZone.runUnary (dart:async/zone.dart:1029:19)
E/flutter (13626): #10 _FutureListener.handleValue (dart:async/future_impl.dart:137:18)
E/flutter (13626): #11 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:678:45)
E/flutter (13626): #12 Future._propagateToListeners (dart:async/future_impl.dart:707:32)
E/flutter (13626): #13 Future._complete (dart:async/future_impl.dart:512:7)
E/flutter (13626): #14 new Future.delayed.<anonymous closure> (dart:async/future.dart:313:16)
E/flutter (13626): #15 _rootRun (dart:async/zone.dart:1120:38)
E/flutter (13626): #16 _CustomZone.run (dart:async/zone.dart:1021:19)
E/flutter (13626): #17 _CustomZone.runGuarded (dart:async/zone.dart:923:7)
E/flutter (13626): #18 _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:963:23)
E/flutter (13626): #19 _rootRun (dart:async/zone.dart:1124:13)
E/flutter (13626): #20 _CustomZone.run (dart:async/zone.dart:1021:19)
E/flutter (13626): #21 _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:947:23)
E/flutter (13626): #22 Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:21:15)
E/flutter (13626): #23 _Timer._runTimers (dart:isolate-patch/timer_impl.dart:382:19)
E/flutter (13626): #24 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:416:5)
E/flutter (13626): #25 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:172:12)
E/flutter (13626):

Answer 1

You have several problems.
1 - your forEach closure looks like you are expecting the JSON to include a list of cars that you are going to add to loadedCars but it does not - there's just one car. That's why extractedData is a Map<String, dynamic> not a List<Map<String, dynamic>>.
2 - that means that the forEach closures is iterating over the members of the map so gets called once with carId='id' and carData=204 and then again with carId='adPrice' and carData=25.0 etc. This is clearly not what you're expecting! The exception happens when you try to parse 'id' into an int.
Given that there's only one car in your current json you can dispense with the loop. You should extract that one car like:
final response = await http.get(url);
final extractedData = json.decode(response.body) as Map<String, dynamic>;
var theOneCar = AddCar(
id: extractedData['id'], // no need for parse either - id is already an int
name: extractedData['adTitle'],
// etc
// etc
print (theOneCar);