how to convert List<Model> to custom data in dart? - flutter

Question

Is there any easy way convert List to other model data?
this is my model:
class Account {
String name;
double balance;
Account({required this.name, required this.balance});
}
class CategoryAccount {
String type;
List<Account> items;
CategoryAccount({required this.type, required this.items});
}
this is sourceData:
List<Account> sourceData = [
Account(name: 'cash', balance: 100),
Account(name: 'cash', balance: 200),
Account(name: 'bank', balance: 300),
Account(name: 'creditor', balance: 400),
];
I want sourceData convert to finalData:
List<CategoryAccount> finalData = [
CategoryAccount(
type: 'cash',
items: [
Account(name: 'cash', balance: 100),
Account(name: 'cash', balance: 200),
],
),
CategoryAccount(
type: 'bank',
items: [
Account(name: 'bank', balance: 300),
],
),
CategoryAccount(
type: 'creditor',
items: [
Account(name: 'creditor', balance: 300),
],
),
];
In Dart I saw the following method for a List : asMap(), but it's not doing what i expect: it use the list index as key. My questions:
Do you known anything in Dart libraries to do this ?

Answer 1

Solution without using a package:
List<CategoryAccount> finalData = [];
for (var se in sourceData) {
final index = finalData.indexWhere((fe) => fe.type == se.name);
if (index >= 0) {
finalData[index].items.add(se);
} else {
finalData.add(CategoryAccount(type: se.name, items: [se]));
}
}
Explanation:
Line 3: Loop through each elements in the sourceData variable
Line 4: Finding the index/position of the CategoryAccount object where the
type matches with the element name
Line 6: Adding the item to the
existing CategoryAccount object if match found (step 4)
Line 8: Else,
create a new CategoryAccount and add the current element
Using Set:
final uniqueEles = sourceData.map((e) => e.name).toSet(); // unique list/set of names [ cash, bank, creditor ]
for (var se in uniqueEles) {
finalData.add(CategoryAccount(
type: se,
items: sourceData.where((el) => el.name == se).toList(),
));
}
a little credit to Irfan Ganatra for the hint. :)

Answer 2

You can use collection package like this:
var grouped = groupBy(
sourceData,
(Account element) => element.name,
);
var finalData = grouped.entries
.map((e) => CategoryAccount(type: e.key, items: e.value))
.toList();
for (var element in finalData) {
print("type = ${element.type}");//cash, bank, creditor
}

Answer 3

and here is kid logic way
List<String> fetch_available_name_from_sourcedata() {
List<String> namelist = [];
for (int x = 0; x < sourceData.length; x++) {
if (!namelist.contains(sourceData[x].name))
namelist.add(sourceData[x].name);
}
return namelist;
}
void main() {
List<CategoryAccount> finaldata = [];
List<String> namelist = fetch_available_name_from_sourcedata();
for (int x = 0; x < namelist.length; x++) {
finaldata.add(CategoryAccount(
type: namelist[x],
items: sourceData
.where((element) => element.name == namelist[x])
.toList()));
}
//now you can see your final data as per your output...
}