Error listing information with rest API with Flutter - flutter

Question

I'm trying to list information from an API remaining on the screen. I have this method:
late List<MyModel> _listAll; // original list fetched from API
late List<MyModel> _displayList;
.
.
void _ListTransaction() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
String token = prefs.getString("userToken") ?? "";
dynamic data = await http.get(Uri.parse('....'), headers: {
'Content-Type': 'application/json',
'Accept': 'application/json',
'Authorization': '$token',
});
List<MyModel> listAll= [];
for (var u in data) {
MyModel myModel = MyModel.fromJson(u);
print(myModel);
listAll.add(myModel);
}
setState(() {
_listAll = listAll;
_displayList = _listAll ;
});
}
Here I get the error:
_TypeError (type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'Iterable')
I also tried this approach:
void _ListTransaction() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
String token = prefs.getString("userToken") ?? "";
dynamic data = await http.get(Uri.parse('....'), headers: {
'Content-Type': 'application/json',
'Accept': 'application/json',
'Authorization': '$token',
});
var list = json.decode(data.body);
print(list);
setState(() {
_listAll = list;
_displayedList = _petrolList;
});
}
But here I get the error:
_TypeError (type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'List')
You guys could help me with this error. I appreciate any comments!
UPDATE
I used this approach too, but to no avail!
Here is the structure of my json.decode(data.body);
MyModel:
class TransactionModel {
int? month;
int? year;
double? balanceFull;
double? balanceMonth;
ExpenseModel? expenseModel;
RevenueModel? revenueModel;
TransactionModel();
Transactions() {
month = 00;
year = 0000;
balanceFull = 0;
balanceMonth = 0;
}
TransactionModel.fromJson(Map<String, dynamic> json) {
month = json['month'];
year = json['year'];
balanceFull = json['balanceFull'];
balanceMonth = json['balanceMonth'];
expenseModel = json['expenseModel'];
revenueModel = json['revenueModel'];
}

Answer 1

I think that the error is that _listAll is a type list of the MyModel, but the list in the "setState" method is Map<String, dynamic>.
I hope to help you.

Answer 2

You should do something like this :
var result = json.decode(data.body);
List<Map<String, dynamic>> list = (result as List).map((e) => e as Map<String, dynamic>).toList();
list.forEach((element) {
_listAll.add(MyModel.fromJson(element));
}
In my case this works because i have a list of Map<String, dynamic> in my result var from my API.
EDIT :
Based on your comment and the screenshot, you should do this :
Map<String, dynamic> result = json.decode(data.body) as Map<String, dynamic>;
result.forEach((element) {
_listAll.add(MyModel.fromJson(element));
}
And in TransactionModel :
TransactionModel.fromJson(Map<String, dynamic> json) {
month = json['month'];
year = json['year'];
balanceFull = json['balanceFull'];
balanceMonth = json['balanceMonth'];
List<Map<String, dynamic>> expenseList = (json["expenses"] as List).map((e) => e as Map<String, dynamic>).toList();
List<Map<String, dynamic>> revenueList = (json["revenues"] as List).map((e) => e as Map<String, dynamic>).toList();
expenseModel = ExpenseModel.fromJson(list.first) // You can loop
revenueModel = RevenueModel.fromJson(revenueList.first) // Same
}
The idea is that you need to convert every nested model you have to Map<String, dynamic> before making the conversion.
I had the sameissue not so long ago.

Answer 3

Last week i had a similar problem.
I solved it using the follow code:
int _offset = 0;
List<Skeleton> array_news = [];
Future<List<Skeleton>> fetchNews(int offset) async {
final response = await http.get(Uri.parse(
'http://192.168.15.5:5000//custom-events?limit=3&offset=$offset'));
return parseNews(response.body);
}
List<Skeleton> parseNews(String responseBody) {
final parsed =
json.decode(responseBody)['events'].cast<Map<String, dynamic>>();
return parsed.map<Skeleton>((json) => Skeleton.fromJson(json)).toList();
}
void executeScript(int offset) async {
List news = await fetchNews(offset);
setState(() {
news.forEach((data) {
array_news.add(Skeleton(
id: data.id,
title: data.title,
page_link: data.page_link,
image_link: data.image_link));
});
});
}
Skeleton code:
class Skeleton {
int id = 0;
String title = '';
String page_link = '';
String image_link = '';
Skeleton(
{required this.id,
required this.title,
required this.page_link,
required this.image_link});
Skeleton.fromJson(Map<String, dynamic> json) {
id = json['id'];
title = json['title'];
page_link = json['page_link'];
image_link = json['image_link'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['id'] = this.id;
data['title'] = this.title;
data['page_link'] = this.page_link;
data['image_link'] = this.image_link;
return data;
}
}
After that just access array_news list data through index.
For example:
array_news[0].title;