Xiao L will show you the data migration adaptation of Hongmeng application upgrade 📱

export default class DataMigration extends BackupExtensionAbility {  

// Backup of old version data

  async onBackup() {  

// Export old sandbox data (such as SQLite database, user files)

    this.copyFile('/old_app/data.db', '/migrate/tmp/data.db');  

  }  



// Recover new version of data

  async onRestore(version: string) {  

if (version.startsWith('1.')) { // Upgrade from 1.x to 2.0

      this.migrateV1ToV2();  

} else if (version.startsWith('2.')) { // Small version upgrade

      this.migrateConfigs();  

    }  

  }  

}  

// Get the old version number

const oldVersion = this.getContext().getBundleVersion();  



// Determine whether specific migration logic is required

if (oldVersion < '2.0.0') {  

this.migrateLegacyData(); // Migrate old format data

}  

// Old version of JSON configuration file

const legacyConfig = await this.readFile('/old_config.json');  



// Convert to binary format (new version uses Protocol Buffers)

const protoConfig = this.convertToProto(legacyConfig);  

await this.writeFile('/new_config.pb', protoConfig);  

// Copy the user picture in the old sandbox to the new sandbox

const oldImagePath = '/data/app/old/files/image.jpg';  

const newImagePath = this.getContext().filesDir + '/image.jpg';  



try {  

  await File.copy(oldImagePath, newImagePath);  

console.log('Image migration is successful');

} catch (error) {  

console.error('Migration failed:', error);

throw new MigrationError('File copy failed');

}  

// Only migrate change data (such as new user settings)

const diffData = this.calculateDiff(oldData, newData);  

await this.saveDiff(diffData);  

// Use transactions to ensure the atomicity of migration steps

async function migrateInTransaction() {  

  try {  

    await this.startTransaction();  

    await this.migrateFiles();  

    await this.updateDatabaseSchema();  

    await this.commitTransaction();  

  } catch (error) {  

await this.rollbackTransaction(); // Rollback on failure

    throw error;  

  }  

}  

// Update migration progress (display percentage)

this.setMigrationProgress(50); // 50% completed

catch (error) {  

  if (error instanceof StorageError) {  

showToast('Insufficient storage space, please clean it and try again');

  } else {  

showToast('Migration failed, please contact customer service');

  }  

}  

// Automatically back up old data before migration

await this.createBackupSnapshot();  

console.log('Before migration backup was created');