How to fix IndexError thrown by LayoutBuilder in Flutter?

Question

I get IndexError thrown by LayoutBuilder .

Error message in VS Code terminal:

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following IndexError was thrown building LayoutBuilder:
RangeError (index): Index out of range: no indices are valid: 0

The relevant error-causing widget was:
  PaginatedDataTable
  PaginatedDataTable:file:///Users/name/development/projects/flutter/project/lib/screens/tabs/a_tab_screen.dart:23:17

When the exception was thrown, this was the stack:
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 266:49      throw_
dart-sdk/lib/_internal/js_dev_runtime/private/js_string.dart 504:7                _get]
packages/project/screens/tabs/a_tab_screen.dart 88:35                    getRow
packages/flutter/src/material/paginated_data_table.dart 346:60                    <fn>
dart-sdk/lib/_internal/js_dev_runtime/private/identity_hash_map.dart 75:23        putIfAbsent
packages/flutter/src/material/paginated_data_table.dart 346:21                    [_getRows]
packages/flutter/src/material/paginated_data_table.dart 539:27                    <fn>
packages/flutter/src/material/paginated_data_table.dart 558:48                    <fn>
packages/flutter/src/widgets/layout_builder.dart 119:70                           layoutCallback
packages/flutter/src/widgets/framework.dart 2605:19                               buildScope
packages/flutter/src/widgets/layout_builder.dart 153:5                            [_layout]
packages/flutter/src/rendering/object.dart 2246:59                                <fn>
packages/flutter/src/rendering/object.dart 1035:15                                [_enableMutationsToDirtySubtrees]
packages/flutter/src/rendering/object.dart 2246:7                                 invokeLayoutCallback
packages/flutter/src/widgets/layout_builder.dart 228:7                            rebuildIfNecessary
packages/flutter/src/widgets/layout_builder.dart 316:5                            performLayout
packages/flutter/src/rendering/object.dart 2135:7                                 layout
packages/flutter/src/rendering/box.dart 2418:11                                   layout
packages/flutter/src/rendering/proxy_box.dart 120:7                               performLayout
packages/flutter/src/rendering/object.dart 2135:7                                 layout
packages/flutter/src/rendering/box.dart 2418:11                                   layout
packages/flutter/src/rendering/proxy_box.dart 120:7                               performLayout
packages/flutter/src/rendering/object.dart 2135:7                                 layout
packages/flutter/src/rendering/box.dart 2418:11                                   layout
packages/flutter/src/rendering/proxy_box.dart 120:7                               performLayout
packages/flutter/src/rendering/custom_paint.dart 552:11                           performLayout
packages/flutter/src/rendering/object.dart 2135:7                                 layout
packages/flutter/src/rendering/box.dart 2418:11                                   layout
packages/flutter/src/rendering/proxy_box.dart 120:7                               performLayout
packages/flutter/src/rendering/proxy_box.dart 1462:11                             performLayout
packages/flutter/src/rendering/object.dart 2135:7                                 layout
packages/flutter/src/rendering/box.dart 2418:11                                   layout
packages/flutter/src/rendering/shifted_box.dart 249:5                             performLayout
packages/flutter/src/rendering/object.dart 2135:7                                 layout
packages/flutter/src/rendering/box.dart 2418:11                                   layout
packages/flutter/src/rendering/proxy_box.dart 120:7                               performLayout
packages/flutter/src/rendering/object.dart 2135:7                                 layout
packages/flutter/src/rendering/box.dart 2418:11                                   layout
packages/flutter/src/rendering/shifted_box.dart 249:5                             performLayout
packages/flutter/src/rendering/object.dart 1973:7                                 [_layoutWithoutResize]
packages/flutter/src/rendering/object.dart 999:17                                 flushLayout
packages/flutter/src/rendering/binding.dart 513:19                                drawFrame
packages/flutter/src/widgets/binding.dart 884:13                                  drawFrame
packages/flutter/src/rendering/binding.dart 378:5                                 [_handlePersistentFrameCallback]
packages/flutter/src/scheduler/binding.dart 1175:15                               [_invokeFrameCallback]
packages/flutter/src/scheduler/binding.dart 1104:9                                handleDrawFrame
packages/flutter/src/scheduler/binding.dart 1015:5                                [_handleDrawFrame]
lib/_engine/engine/platform_dispatcher.dart 1168:13                               invoke
lib/_engine/engine/platform_dispatcher.dart 219:5                                 invokeOnDrawFrame
lib/_engine/engine/initialization.dart 195:45                                     <fn>
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 334:14  _checkAndCall
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 339:39  dcall

════════════════════════════════════════════════════════════════════════════════════════════════════

My code:

StreamBuilder<List<Model>>(
  stream: stream,
  builder: (context, snapshot) {
    return snapshot.data == null
        ? Container()
        : PaginatedDataTable(
            source: MyData(list: snapshot.data!),
            columns: [
              DataColumn(
                label: Text(
                  "Name",
                  maxLines: 1,
                  overflow: TextOverflow.ellipsis,
                ),
              ),
              DataColumn(
                label: Text(
                  "Email",
                  maxLines: 1,
                  overflow: TextOverflow.ellipsis,
                ),
              ),
            ],
            columnSpacing: 20,
            horizontalMargin: 10,
            rowsPerPage: 10,
            showCheckboxColumn: false,
          );
  },
),

---

class MyData extends DataTableSource {
  MyData({required this.list}) : super();
  final List<Model> list;

  @override
  bool get isRowCountApproximate => false;
  @override
  int get rowCount => list.length;
  @override
  int get selectedRowCount => 0;
  @override
  DataRow getRow(int index) {
    return DataRow(
      cells: [
        DataCell(
          Text(
            list[index].name,
          ),
        ),
        DataCell(
          Text(
            list[index].email,
          ),
        ),
      ],
    );
  }
}

Feel free to comment if you need more information!

How to fix this error? I would appreciate any help. Thank you in advance!

Answer 1

You missed the index param in the MyData class. The getRow() method must return DataRow using DataRow.byIndex(…) and inside the byIndex() method you should set the index parameter.

Take a look at this article.