如何向擴展DataTableSource的類提供數據

Question

使用PaginatedDataTable在抖動上顯示數據

我必須提供一個從DataTableSource擴展的類的源，但是我無法像在通過錯誤嘗試擴展DataTableSource的類上提供任何數據

“只能在初始值設定項flutter中訪問靜態成員”

那么如何從外部提供DataTableSource的初始數據？

class TransactionAcrossMonthsItem {
  final String transactionName;
  final int monthOf1;
  final int monthOf2;
  final int monthOf3;
  final int monthOf4;
  final int monthOf5;
  final int monthOf6;
  final int monthOf7;
  final int monthOf8;
  final int monthOf9;
  final int monthOf10;
  final int monthOf11;
  final int monthOf12;
  final int totalCount;
  final double percent;
  bool selected = false;
  TransactionAcrossMonthsItem(
      this.transactionName,
      this.monthOf1,
      this.monthOf2,
      this.monthOf3,
      this.monthOf4,
      this.monthOf5,
      this.monthOf6,
      this.monthOf7,
      this.monthOf8,
      this.monthOf9,
      this.monthOf10,
      this.monthOf11,
      this.monthOf12,
      this.totalCount,
      this.percent);
}

class TransactionsAcrossDataSource extends DataTableSource {
  final List<TransactionAcrossMonthsItem> _data;

  int _selectedCount = 0;

  TransactionsAcrossDataSource(this._data);
...........
}




class DetailedReportPage extends StatefulWidget {
  final int yearOf;
  DetailedReportPage({this.yearOf});

  @override
  State<StatefulWidget> createState() {
    return _DetailedReportPageState();
  }
}

class _DetailedReportPageState extends State<DetailedReportPage> {
  int _rowsPerPage = PaginatedDataTable.defaultRowsPerPage;
  int _sortColumnIndex;
  bool _sortAscending = true;

   List<TransactionAcrossMonthsItem> _data = [
    TransactionAcrossMonthsItem(
        'eDirham', 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 1000, 70),
    TransactionAcrossMonthsItem(
        'tasheel', 120, 120, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 2000, 20),
    TransactionAcrossMonthsItem(
        'immgration', 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 3000, 10)
  ];
  var _dataSource = TransactionsAcrossDataSource(_data);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: .....
      body: createReport(),
    );
  }



  Widget createReport() {
    return ListView(padding: const EdgeInsets.all(20.0), children: <Widget>[
      PaginatedDataTable(
        header: Text('Year of ${widget.yearOf}'),
        rowsPerPage: _rowsPerPage,
        onRowsPerPageChanged: (int value) {
          setState(() {
            _rowsPerPage = value;
          });
        },
        sortColumnIndex: _sortColumnIndex,
        sortAscending: _sortAscending,
        // onSelectAll: _dataSource._selectAll,
        columns: getColumns(),
        source: _dataSource,
      )
    ]);
  }

  List<DataColumn> getColumns() {
    return [
      DataColumn(
        label: Text('Name'),
        ......
      ),
      DataColumn(
        .....
      ),
      ......
    ];
  }
}

Answer 1

更改

 var _dataSource = TransactionsAcrossDataSource(_data);

至

TransactionsAcrossDataSource _dataSource; 

並移動

_dataSource = TransactionsAcrossDataSource(_data); 

到構造函數。

因為您不能在類的方法或構造函數之外具有隨機代碼。