rearrange the list map in Flutter - list

Question

I have a list map like below :
[
data{text: hello, date: 2020-09-11}, data{text: hi, date: 2020-09-12},
data{text: why, date: 2020-09-11}, data{text: how, date: 2020-09-10},
data{text: when, date: 2020-09-11}, data{text:flutter, date: 2020-09-12}
]
and what I want to get is this :
{
2020-09-10 : [how],
2020-09-11 : [hello, why, when],
2020-09-12 : [hi, flutter]
}
I'm a bit confusing between list<map> and list , I have no idea how to solve this.
I already know remove duplicate things with method toSet().toList().
Is there any method related with this? Thanks in advance.
-------------------- After following answer -----------------------
date => createTime, text => repeat
loadRepeat() async {
DBHelperRepeat sd = DBHelperRepeat();
var list = await sd.repeats();
List newList = [];
if (list[0].createTime == list[1].createTime) {
newList.add({
'date': list[0].createTime,
'repeat': list[0].repeat + ',' + list[1].createTime
});
} else {
newList.add({'date': list[0].createTime, 'repeat': list[0].repeat});
newList.add({'date': list[1].createTime, 'repeat': list[1].repeat});
}
for (int i = 2; i < list.length; i++) {
if (list[i].createTime == newList.last.createTime) {
newList.last.repeat += ',' + list[i].repeat;
} else {
newList.add(list[i]);
}
}
print(newList);
}
and here's my sqlite db code
repeat.dart
class Repeat {
final String repeat;
final String createTime;
final int year;
final int month;
final int date;
Repeat({this.repeat, this.createTime, this.year, this.month, this.date});
Map<String, dynamic> toMap() {
return {
'repeat': repeat,
'createTime': createTime,
'year': year,
'month': month,
'date': date
};
}
#override
String toString() {
return '{repeat: $repeat, createTime: $createTime, year: $year, month: $month, date: $date}';
}
}
db_repeat.dart
class DBHelperRepeat {
var _db;
Future<Database> get database async {
if (_db != null) return _db;
_db = openDatabase(
join(await getDatabasesPath(), 'repeats.db'),
onCreate: (db, version) {
return db.execute(
"CREATE TABLE repeats(repeat TEXT, createTime TEXT, year INT, month INT, date INT)",
);
},
version: 1,
);
return _db;
}
Future<void> insertRepeat(Repeat repeat) async {
final db = await database;
await db.insert('repeats', repeat.toMap(),
conflictAlgorithm: ConflictAlgorithm.replace);
}
Future<List<Repeat>> repeats() async {
final db = await database;
final List<Map<String, dynamic>> maps = await db.query('repeats');
return List.generate(maps.length, (i) {
return Repeat(
repeat: maps[i]['repeat'],
createTime: maps[i]['createTime'],
year: maps[i]['year'],
month: maps[i]['month'],
date: maps[i]['date']);
});
}
example data list:
[{repeat: repeat1, createTime: 2020-09-13, year: 2020, month: 9, date: 13}]

Answer 1

Maybe this can help you:
DBHelperRepeat sd = DBHelperRepeat();
List<Repeat> list = await sd.repeats();
list.sort((a,b)=> a.createTime.compareTo(b.createTime));
List<Repeat> newList = [];
if(list.length == 0){
return newList;
} else if(list.length == 1){
newList.addAll(list);
return newList;
}
if (list[0].createTime == list[1].createTime) {
newList.add(
Repeat(
createTime: list[0].createTime,
repeat: list[0].repeat+', '+list[1].repeat,
date: list[0].date,
month: list[0].month,
year: list[0].year
)
);
} else {
newList.add(list[0]);
newList.add(list[1]);
}
if(list.length < 3){
return newList;
}
for (int i = 2; i < list.length; i++) {
if (list[i].createTime == newList.last.createTime) {
Repeat last = newList.last;
Repeat repeat = Repeat(
createTime: last.createTime,
repeat: last.repeat+', ' + list[i].repeat,
date: last.date,
month: last.month,
year: last.year
);
newList.removeLast();
newList.add(repeat);
} else {
newList.add(list[i]);
}
}
newList.forEach((element) {
print(element.createTime);
print(element.repeat);
});