How to map dynamic lists in flutter

Question

Ok so I am kind of new to flutter, but I trying to fetch and display items in a list using map.

class TransactionTable extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return TransactionTableState();
  }
}

class TransactionTableState extends State {
  final List moneyTransactions = [
    new MoneyTransactionModel(
        id: "1",
        productId: "lime",
        entryType: "sold",
        quantity: "60kg",
        unitPrice: "240rwf/kg",
        paidBy: "mtn",
        createdAt: "2020-04-20T00:15:08.932Z"),
    new MoneyTransactionModel(
        id: "2",
        productId: "lime",
        entryType: "sold",
        quantity: "60kg",
        unitPrice: "240rwf/kg",
        paidBy: "mtn",
        createdAt: "2020-04-20T00:15:08.932Z"),
    new MoneyTransactionModel(
        id: "3",
        productId: "lime",
        entryType: "sold",
        quantity: "60kg",
        unitPrice: "240rwf/kg",
        paidBy: "mtn",
        createdAt: "2020-04-20T00:15:08.932Z"),
    new MoneyTransactionModel(
        id: "4",
        productId: "lime",
        entryType: "sold",
        quantity: "60kg",
        unitPrice: "240rwf/kg",
        paidBy: "mtn",
        createdAt: "2020-04-20T00:15:08.932Z"),
  ];
 
  Widget build(BuildContext context) {
    // return 
    return Column(
    children: <Widget>[
      moneyTransactions.map((e) => MyListTile()); // i need to the the loop here
    ],
    );
  }
}

MyListTile is a widget supposed to display one item in the moneyTransactions list

Herry · Accepted Answer · 2020-08-05 12:17:26Z

1

You are inserting a List into an existing List, your build method should look like this:

Widget build(BuildContext context) {
    return Column(
        children: moneyTransactions.map((e) => MyListTile()).toList();
    );
}

Now for each item in the List, one instance of MyListTile is generated.

To have actual access to the information of the MoneyTransaction you would have to pass the object as a parameter in the constructor of MyListTile.

answered Aug 5, 2020 at 12:17

Herry

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Comments

Birju Vachhani · Accepted Answer · 2020-08-05 12:18:41Z

1

You are nesting to lists and that's why it is not working. Also, you need to call toList() after the map() operation. Try following code:

Method 1

Widget build(BuildContext context) {
  // return 
  return Column(
    children: moneyTransactions.map((e) => MyListTile()).toList(),
  );
}

Method 2

Widget build(BuildContext context) {
  return Column(
  children: <Widget>[
      ...moneyTransactions.map((e) => MyListTile()).toList(),
    ],
  );
}

answered Aug 5, 2020 at 12:18

Birju Vachhani

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