How to Protect Excel workbook programmatically in Flutter?

Flutter XIsIO library is used to create and modify Excel documents. Using this library, you can also protect Excel Workbook elements with or without a password using Flutter. Workbook protection is used to protect the structure of workbook elements from viewing, moving, editing, or deleting important data.

Steps to protect the workbook of the Excel document programmatically.

Step 1: Create a new Flutter application project.

1. Open Visual Studio Code (after installing the Dart and Flutter extensions as stated in this setup editor page).
2. Click View -> Command Palette…

3. Type Flutter and choose Flutter: New Project.

4. Enter the project name and press the Enter button.
5. Now choose the location of the project.

Step 2: Add the following code in your pubspec.yaml file to install the syncfusion flutter xlsio package in your application. It will be automatically downloaded from the pub once you trigger the flutter pub get comment or Get packages option from the Visual Studio Code.

dependencies:
   syncfusion_flutter_xlsio: ^18.4.31-beta

Import the following package in your main.dart file.

import 'package:syncfusion_flutter_xlsio/xlsio.dart' ;

Step 3: Add the following code in the lib/main.dart file to create a simple button.

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            FlatButton(
              child: const Text(
                'Generate Excel',
                style: TextStyle(color: Colors.white),
              ),
              color: Colors.blue,
              onPressed: _protectWorkbook,
            )
          ],
        ),
      ),
    );
  }

Step 4: Add the following code to the _protectWorkbook() function to protect workbook of an Excel document programmatically.

Future<void> _protectWorkbook() async {
    // Create a Excel document.
    // Creating a workbook.
    final Workbook workbook = Workbook();
 
    // Accessing via index
    final Worksheet sheet = workbook.worksheets[0];
 
    // Assigning text to cells
    final Range range = sheet.getRangeByName('A1');
    range.setText('WorkBook Protected');
 
    final bool isProtectWindow = true;
    final bool isProtectContent = true;
 
    // Protect Workbook
    workbook.protect(isProtectWindow, isProtectContent, 'password');
 
    // Save and launch the excel.
    final List<int> bytes = workbook.saveAsStream();
 
    // Dispose the document.
    workbook.dispose();
}

Step 5: Use the following code to save and launch the generated Excel file.

1. Add the following dependencies in your pubspec.yaml file.

   path_provider: ^1.6.7
   open_file: ^3.0.1   #Open source library to launch the Excel file in mobile devices
   

2. Import the following packages in your main.dart file.

   import 'dart:io'; 
   import 'package:path_provider/path_provider.dart';
   import 'package:open_file/open_file.dart';
   

3. Include the following code snippet in the _protectWorkbook() method to open the Excel document in the mobile‘s default application (any Excel application).

   // Get the storage folder location using path_provider package.
   final Directory directory = await getExternalStorageDirectory();
   // Get directory path
   final String path = directory.path;
   // Create an empty file to write Excel data
   final File file = File('$path/ProtectWorkbook.xlsx');
   // Write Excel data
   await file.writeAsBytes(bytes, flush: true);
   // Launch the file (used open_file package)
   await OpenFile.open('$path/ProtectWorkbook.xlsx');
   

Step 6: Run the sample using the flutter run command. This will protect the workbook of the Excel document.

After the application launches, you will get the Excel document as follows.

Output Excel document created using XlsIO

You can download the complete work sample from protect-excel-workbook.zip.

Take a moment to peruse the documentation of security,  where you can find other protection options like protect worksheet and protect cell in Excel. Also, finds the features like images, charts and more with code examples.