Data Migration Adaptation in HarmonyOS Application Upgrade Scenarios

This article aims to deeply explore the technical details of file management in the Huawei HarmonyOS Next system (up to API 12 as of now), and is summarized based on actual development practices.
It mainly serves as a carrier for technical sharing and communication. Mistakes and omissions are inevitable. Colleagues are welcome to put forward valuable opinions and questions so that we can make progress together.
This article is original content, and any form of reprint must indicate the source and the original author.

Introduction
With the continuous development of HarmonyOS, application upgrades are inevitable. During the application upgrade process, how to ensure the security and continuity of user data is an important issue that we developers need to pay attention to. HarmonyOS provides a data migration framework to help developers achieve data migration in application upgrade scenarios and ensure that user data is seamlessly migrated to the new version of the application.
1. Application Scenarios and Requirements for Data Migration
When a HarmonyOS application is upgraded to a new version, user data needs to be migrated to ensure that the new version of the application can inherit the original data. The main scenarios for data migration include:

• Application Version Update: When an application releases a new version, users need to update the application, and the new version of the application needs to inherit the original data.
• Device Upgrade: When a user upgrades the device to a higher version of HarmonyOS, the application needs to migrate data to the new system. 2. Architecture of the Data Migration Framework The HarmonyOS data migration framework mainly consists of the following components:

3. Implementation of BackupExtensionAbility in Migration
BackupExtensionAbility is the core component of the data migration framework, and it is responsible for executing backup and restore tasks. Developers can implement the backup and restore logic of application data by customizing the onBackup and onRestore methods of BackupExtensionAbility.
4. Sample Code: Implementation of Data Restoration
The following sample code shows how to use BackupExtensionAbility to implement data restoration in the application upgrade scenario:

import { BackupExtensionAbility, BundleVersion } from '@kit.CoreFileKit';
export default class BackupExtension extends BackupExtensionAbility {
  async onRestore(bundleVersion: BundleVersion) {
    // Check if the device is upgraded from HarmonyOS to HarmonyOS NEXT
    if (bundleVersion.name.startsWith("0.0.0.0")) {
      console.log('Device upgraded from HarmonyOS to HarmonyOS NEXT');
      // Implement the data migration logic from HarmonyOS to HarmonyOS NEXT
      // For example, migrate APK application data to the HarmonyOS application sandbox
      //...
    } else {
      console.log('Device upgraded within HarmonyOS NEXT');
      // Implement the data migration logic for internal upgrades within HarmonyOS NEXT
      // For example, migrate the old version application data to the new version application sandbox
      //...
    }
  }
}

5. Best Practices for Data Migration

• Data Migration Testing: Before the application is released, sufficient data migration testing is required to ensure the integrity and security of data migration.
  • Unit Testing: Perform unit testing on the data migration logic to ensure the correctness of each step.
  • Integration Testing: Test in a complete application environment to verify the overall process of data migration.
  • User Testing: Invite users to participate in testing, collect user feedback, and optimize.
• User Data Backup: Before performing data migration, it is recommended that users back up important data to prevent data loss.
• Error Handling: During the data migration process, error handling is required to ensure the reliability of the migration process.
  • Exception Catching: Catch and handle possible exceptions, such as file non-existence, insufficient read and write permissions, etc.
  • Log Recording: Record log information during the data migration process to facilitate problem troubleshooting.
• User Experience Optimization: During the data migration process, the user experience needs to be optimized, such as providing progress prompts, error messages, etc.
  • Progress Prompt: Display the data migration progress to let users understand the migration process.
  • Error Message: Provide clear error messages to help users solve problems. 6. Conclusion The HarmonyOS data migration framework provides us developers with a convenient and secure way to achieve data migration in application upgrade scenarios and ensures that user data is seamlessly migrated to the new version of the application. We can take advantage of the data migration framework to easily implement the data migration function and provide users with a better application experience. At the same time, we also need to pay attention to aspects such as data migration testing, user data backup, error handling, and user experience optimization to ensure the reliability of data migration and the user experience.