How to get the value without "index" in Flutter - flutter

Question

How to get an average number of star (means result should get 1.5) ?
Note: The value to get is without index because it is not under ListView.builder
Below is the sample json code and this is how what i tried till now.
JSON
{
"message": "feedbacks for restaurant branch returened",
"data": [
{
"id": "4",
"comment": "Investor Operations Coordinator",
"star": 1,
}
{
"id": "4",
"comment": "Investor Operations Coordinator",
"star": 2,
}
]
}
DART
Widget buildReviewNumbers(List<FeedbacksData> data) {
return Column(
children: [
for (int index = 0; index < data.length; index++)
Text(
data[index].star.toString(),
style: TextStyle(fontWeight: FontWeight.w900, fontSize: 30.0),
),
],
);
}

Answer 1

paste it on DartPad
final map = {
"message": "feedbacks for restaurant branch returened",
"data": [
{
"id": "4",
"comment": "Investor Operations Coordinator",
"star": 1,
},
{
"id": "4",
"comment": "Investor Operations Coordinator",
"star": 2,
}
]
};
void main() {
final data = map['data'] as List<Map<String, dynamic>>;
var total = 0;
data.forEach((e) {
total += e['star'] as int;
});
print(total/ data.length);
}
For your case:
Widget buildReviewNumbers(List<FeedbacksData> data) {
var total = 0;
data.forEach((e) {
total += e.star;
});
return Text(
'${total/data.length}',
style: TextStyle(fontWeight: FontWeight.w900, fontSize:30.0),
);
}

Answer 2

Your jsondata of type Map dynamic has to be converted to a list of Feedbacks according to your code. Once done just use the map operator to loop through your data.
Column(
children: data.map((item) => Text(item.star.toString())).toList();
);
For lack of more info on what Feedbacks data looks like i shortened it to this.

Answer 3

You can use reduce to get the total value of ratings, then divide it by the number of ratings. See the concrete example on DartPad.