how to filter data based on tag in flutter? - flutter

Question

I am creating a screen where need to filter data based on category types and transaction type.
Its working fine but it results null when filter list is empty, I can manage with some logically tricks but it will be lengthy coding..
is there any other better way to filter data properly even if filter tag is empty and
should display all records based on transaction type
like
transactiontype='Expense'
filtertags=[]
result:
it should display all expense transactions
transactiontype='Expense'
filtertags=['Food']
result:
it should display all expense transactions of Food
class TransactionModel {
String category;
double amount;
bool isExpense;
TransactionModel(
{required this.category, required this.amount, this.isExpense = true});
String printData() {
return 'Category:' +
category +
' Amount: ' +
amount.toString() +
'isExpense:' +
isExpense.toString();
}
}
List<String> _filtertags = ['Food'];// if this list is empty it should show all posible records
String transactiontype = 'Expense';
List<TransactionModel> transactions = [
TransactionModel(
category: 'Shopping',
amount: 4300,
),
TransactionModel(category: 'Food', amount: 2200,isExpense: true),
TransactionModel(category: 'Loan', amount: 400, isExpense: false),
TransactionModel(category: 'Food', amount: 300,isExpense: false),
TransactionModel(category: 'Other', amount: 100,isExpense: true),
];
void main() {
var resultdata = transactiontype == 'All'
? transactions
.where((element) => _filtertags.contains(element.category))
.toList()
: transactiontype == 'Expense'
? transactions
.where((element) =>
_filtertags.contains(element.category) &&
element.isExpense == true)
.toList()
: transactions
.where((element) =>
_filtertags.contains(element.category) &&
element.isExpense == false)
.toList();
for (var x in resultdata) {
print(x.printData());
}
}

Answer 1

You can simplify like
var result = [];
if (transactionType == 'All' || transactionType.isEmpty) {
result = transactions.toList();
} else {
bool isExpense = transactionType == 'Expense';
//add more filter when needed and comare with model class
result = transactions
.where((element) =>
_filterTags.contains(element.category) &&
element.isExpense == isExpense)
.toList();
}
for (var x in result) {
print(x.toString());
}
});