Data grid export Error Unexpected null value
Hi friends,
I'm trying to export data to PDF, but I get a strange error: Error: Unexpected null value like below:
My function:
What can cause this error :( ? Please help me any suggestion will be much appreciated!
Thanks in advance!
Hi Dorin Buraca,
Based on the provided information and call stack
details, it seems that this issue might be arising due to a mismatch in the
column names between `GridColumn.columnName` and `DataGridCell.columnName`.
In our source, we retrieve values from the cell based on the column name
specified in both `GridColumn.columnName` and `DataGridCell.columnName`. We
have conducted testing with a simple sample using the latest version of the
package, and it is functioning correctly on our end.
We kindly request you to verify that the column names are consistent between `GridColumn.columnName` and `DataGridCell.columnName` in your sample.
For your convenience, we have
provided a simple sample that we extensively tested on our end. Please review
the following code snippet and the attached sample for more comprehensive
information.
|
In GridColumn: Widget build(BuildContext context) { return Scaffold( appBar: AppBar(title: const Text('SfDatagrid Demo')), body: Column(children: [ const Padding(padding: EdgeInsets.only(top: 30)), SizedBox( child: ElevatedButton.icon( onPressed: () async { final PdfDocument document = dataGridKey.currentState!.exportToPdfDocument( fitAllColumnsInOnePage: true, ); final List<int> data = document.saveSync(); await helper.saveAndLaunchFile(data, 'DataGrid.pdf'); document.dispose(); }, icon: const Icon(Icons.print), label: const Text('Export DataGrid to PDF'), )), Expanded( child: Card( margin: const EdgeInsets.all(30), child: SfDataGrid( source: _employeeDataSource, key: dataGridKey, columns: <GridColumn>[ GridColumn( columnName: 'id', label: Container( padding: const EdgeInsets.symmetric(horizontal: 16.0), alignment: Alignment.center, child: const Text( 'ID', ))), GridColumn( columnName: 'name', label: Container( padding: const EdgeInsets.symmetric(horizontal: 16.0), alignment: Alignment.center, child: const Text('Name'))), GridColumn( columnName: 'designation', label: Container( padding: const EdgeInsets.symmetric(horizontal: 16.0), alignment: Alignment.center, child: const Text('Designation'))), GridColumn( columnName: 'salary', label: Container( padding: const EdgeInsets.symmetric(horizontal: 16.0), alignment: Alignment.center, child: const Text('Salary'))), ], columnWidthMode: ColumnWidthMode.fill, ), )) ])); } } EmployeeDataSource(List<Employee> employees) { buildDataGridRow(employees); } void buildDataGridRow(List<Employee> employeeData) { dataGridRow = employeeData.map<DataGridRow>((employee) { return DataGridRow(cells: [ DataGridCell<int>(columnName: 'id', value: employee.id), DataGridCell<String>(columnName: 'name', value: employee.name), DataGridCell<String>( columnName: 'designation', value: employee.designation), DataGridCell<int>(columnName: 'salary', value: employee.salary), ]); }).toList(); } … } |
Regards,
Tamilarasan
Attachment: Sample_464372fd.zip
Hi Tamilarasan,
Thanks for your quick reply, was very helpful to me, I found the bug in my case.
What I'm wondering now is how can I redefine the Column name for the exported document, because by default I get the value from the GridColumn.columnName ... but my first concern is how can I export only the selected items from the list, not the entire one?
This is a major option for me :(
Thanks in advance!
Dorin Buraca,
Regarding: how can I redefine the Column name for the exported
document.
To customize the cell value during PDF export, you can directly set the cell value in the PdfGrid using the PdfCell property available in the argument of the cellExport callback. For more detailed information, please refer to the following code snippet.
|
@override Widget build(BuildContext context) { return Scaffold( appBar: AppBar(title: const Text('SfDatagrid Demo')), body: Column(children: [ const Padding(padding: EdgeInsets.only(top: 30)), SizedBox( child: ElevatedButton.icon( onPressed: () async { final PdfDocument document = dataGridKey.currentState!.exportToPdfDocument( fitAllColumnsInOnePage: true, cellExport: (details) { if (details.cellType == DataGridExportCellType.columnHeader) { if (details.cellValue == 'id') { details.pdfCell.value = 'Employee ID'; } else if (details.cellValue == 'name') { details.pdfCell.value = 'Employee Name'; } else if (details.cellValue == 'designation') { details.pdfCell.value = 'Employee Designation'; } else if (details.cellValue == 'salary') { details.pdfCell.value = 'Employee Salary'; } } }, ); final List<int> data = document.saveSync(); await helper.saveAndLaunchFile(data, 'DataGrid.pdf'); document.dispose(); }, icon: const Icon(Icons.print), label: const Text('Export DataGrid to PDF'), )), Expanded( child: Card( margin: const EdgeInsets.all(30), child: SfDataGrid( source: _employeeDataSource, controller: dataGridController, selectionMode: SelectionMode.multiple, key: dataGridKey, columns: getColumns, columnWidthMode: ColumnWidthMode.fill, ), )) ])); } |
Regarding: how can I export only the selected items from the list,
not the entire one?
To export selected items in the DataGrid, utilize the rows parameter in exportToPdfDocument and exportToPdfGrid methods. Pass the selected rows from DataGridController.selectedRows to the rows parameter to export only the selected rows. For further guidance, please refer to the following code snippet.
|
@override Widget build(BuildContext context) { return Scaffold( appBar: AppBar(title: const Text('SfDatagrid Demo')), body: Column(children: [ const Padding(padding: EdgeInsets.only(top: 30)), SizedBox( child: ElevatedButton.icon( onPressed: () async { final PdfDocument document = dataGridKey.currentState!.exportToPdfDocument( fitAllColumnsInOnePage: true, rows: dataGridController.selectedRows, ); final List<int> data = document.saveSync(); await helper.saveAndLaunchFile(data, 'DataGrid.pdf'); document.dispose(); }, icon: const Icon(Icons.print), label: const Text('Export DataGrid Selected Rows to PDF'), )), Expanded( child: Card( margin: const EdgeInsets.all(30), child: SfDataGrid( source: _employeeDataSource, controller: dataGridController, selectionMode: SelectionMode.multiple, key: dataGridKey, columns: getColumns, columnWidthMode: ColumnWidthMode.fill, ), )) ])); } |
We have also provided a simple sample for your
reference, demonstrating how to export selected items and customize the header
text during the export process. Check the attached sample for more information.
Attachment: Sample_80912740.zip
Hi
Tamilarasan,
Thanks a lot for your great support, I managed to make them work!
One question, how can I define the Headers titles like in Pdf Export, as well for Excel Export?
if (details.cellType == DataGridExportCellType.columnHeader) {
if (details.cellValue == 'id') {
details.pdfCell.value = 'Employee ID';
} else if (details.cellValue == 'name') {
details.pdfCell.value = 'Employee Name';
} else if (details.cellValue == 'designation') {
details.pdfCell.value = 'Employee Designation';
} else if (details.cellValue == 'salary') {
details.pdfCell.value = 'Employee Salary';
}
}
},
2. Is there a possibility to modify the cell data for excel export?
Thanks in advance!
Hi Dorin,
By default, the DataGrid supports cell customization for both Excel and PDF while exporting. Please refer to the User Guide (UG) document to learn more about these features.
Export to Excel - https://help.syncfusion.com/flutter/datagrid/export-to-excel#customize-cell-values-while-exporting
Export to PDF - https://help.syncfusion.com/flutter/datagrid/export-to-pdf#customize-cell-values-while-exporting
If this information is helpful, kindly consider accepting it as the solution so that other members can locate it more quickly.
Regards,
Nirmalkumar.
Hi
Nirmalkumar,
Thanks for your reply, the solution for custom headers in excel is:
Thanks!
