How make async api calls inside loop and complete loop with all data from api call. Due to async I'm losing that part of data - flutter

Question

I'm reading json List from device memory and want to perform some operations on it's components.
When I load that list I start loop where I check each item of that list.
While in loop I add each item to new List to have updated List after loop ends so I could save it on device memory.
If some conditions are true then I use future async http call to get updated data
then theoretically I update that item of the List while staying inside loop. And thus after loop ends I must have updated Json List ready to be saved on device memory.
Problem is that While I http call inside loop, the answer delays, loop ends and new Json List is being constructed and saved on memory without the component that was supposed to be updated.
Is there any way to force wait the whole loop or something else ?
Here is the code
Future<void> readStoredData() async {
try {
final prefs = await SharedPreferences.getInstance();
_rawJsonListE = prefs.getStringList('storedData');
List<String> rawJsonListNEW = [];
bool _isNeedUpdate = false;
_rawJsonListE!.forEach((item) async {
if (someCondition with item Data) {
_isNeedUpdate = true;
await makeHttpCallFutureAwaitFunction(item).then((_) {
rawJsonListNEW.add(updatedItem);
});
} else {
rawJsonListNEW.add(item);
}
});
if (_isNeedUpdate) prefs.setStringList('storedData', rawJsonListNEW);
}
notifyListeners();
} catch (error) {
print('Error : ${error}');
throw error;
}

Answer 1

You can separate the refreshing data part to another function.
// Just need to check _rawJsonListE is empty or not
_isNeedUpdate = _rawJsonListE.isNotEmpty();
Create a new function.
Future<List<String>> checkDataAndRefresh(List<String> _rawJsonListE) async {
List<String> rawJsonListNEW = [];
_rawJsonListE!.forEach((item) async {
if (someCondition with item Data) {
final String newString = await makeHttpCallFutureAwaitFunction(item);
rawJsonListNEW.add(newString);
} else {
rawJsonListNEW.add(item);
}
});
return rawJsonListNEW;
}
And if _isNeedUpdate is true, do work.
if (_isNeedUpdate)
final List<String> newData = await checkDataAndRefresh(_rawJsonListE);
prefs.setStringList('storedData', newData);