How to reverse Map values in dart - flutter

Question

I am trying to reverse Map values. But didin't get proper one,
here my Map
Map<String, dynamic> details = {
"sms": {
"very_low": false,
"low": false,
"medium": false,
"high": false,
"very_high": true
}
};
I want to get like this ;
{
sms: {
very_high: true,
high: false,
medium: false,
low: false,
very_low: false
}
}
If Anyone please share your ideas

Answer 1

Let's say this is your "map":
Map<String, dynamic> details = {
"sms": {
"very_low": false,
"low": false,
"medium": false,
"high": false,
"very_high": true
}
};
You can use this extension:
extension NewMap on Map {
Map reverse() => Map.fromEntries(entries.toList().reversed);
}
and use it like this:
details["sms"] = (details["sms"] as Map<String, dynamic>).reverse();
print("details =$details"); //details = {sms: {very_high: true, high: false, medium: false, low: false, very_low: false}}

Answer 2

A solution that works for any Map no matter how much nested it is:
Object reverse(Object object) {
if (object is Map) {
return Map.fromEntries(object.entries.map((e) => MapEntry(e.key, reverse(e.value))).toList().reversed);
}
return object;
}
usage:
void main() async {
Map<String, dynamic> details = {
"sms": {
"very_low": false,
"low": false,
"medium": false,
"high": false,
"very_high": true
}
};
var newDetails = reverse(details);
print(details);
//{sms: {very_low: false, low: false, medium: false, high: false, very_high: true}}
print(newDetails);
//{sms: {very_high: true, high: false, medium: false, low: false, very_low: false}}
}

Answer 3

final details =
{"sms" : {"very_low" : false, "very_hight" : true, "very_medium" : false} };
final outerMap = {};
for(final m in details.entries){
final reversedList = m.value.entries.toList().reversed;
final innerMap = {};
innerMap.addEntries(reversedList);
outerMap.addAll({m.key : innerMap});
}
print(outerMap);
//details = {sms: {very_medium: false, very_hight: true, very_low: false}}

Answer 4

import 'dart:convert';
Map<String, dynamic> yourMap = {
"sms": {
"very_low": false,
"low": false,
"medium": false,
"high": false,
"very_high": true
}
};
Map<K, V> reverse<K, V>(Map<K, V> source) {
return Map<K, V>.fromEntries(source.entries.toList().reversed);
}
main() {
print(jsonEncode(yourMap));
yourMap['sms'] = reverse(yourMap['sms']);
print(jsonEncode(yourMap));
}
Prints:
{"sms":{"very_low":false,"low":false,"medium":false,"high":false,"very_high":true}}
{"sms":{"very_high":true,"high":false,"medium":false,"low":false,"very_low":false}}
Please note that this only works because Map behind the scenes constructs a LinkedHashMap that is insertion-ordered. If you construct other types of Map that are not, this may not work. Generally speaking, it might be wise to not rely on the order of items in a Map because it is not guaranteed unless you created the Map yourself.
Since this looks like it should be JSON: don't bother sorting this. It is supposed to be a machine-to-machine protocol, machines do not care if it looks neat. The less uneccessary code you write, the less bugs you produce.