Implementing data synchronization between IndexedDB and PouchDB

01 Oct 2023

Data synchronization is a crucial aspect of modern web applications, as it allows users to seamlessly switch between offline and online modes without losing any data. In this blog post, we will explore how to implement data synchronization between IndexedDB and PouchDB.

Background

IndexedDB is a browser-based database API that allows web applications to store large amounts of structured data. PouchDB, on the other hand, is a JavaScript library that enables developers to build offline-first applications by synchronizing data with CouchDB or other compatible databases.

The Sync Process

To implement data synchronization between IndexedDB and PouchDB, we need to follow these steps:

Initialize PouchDB: First, we need to initialize PouchDB by creating a new instance. We can specify the database name and other options during initialization.
```
 const dbName = 'my-database';
 const pouchDB = new PouchDB(dbName);
```

Set up Replication: To synchronize data between IndexedDB and PouchDB, we need to establish replication between the two databases. This allows changes made in one database to be automatically replicated to the other.

 async function synchronizeData() {
     try {
         const db = await indexedDB.open('my-indexeddb');
         const pouchDBChanges = pouchDB.sync(db, { live: true, retry: true });
         const indexedDBChanges = db.sync(pouchDB, { live: true, retry: true });

         pouchDBChanges.on('change', info => {
             console.log('PouchDB changes:', info);
         });

         indexedDBChanges.on('change', info => {
             console.log('IndexedDB changes:', info);
         });

     } catch (error) {
         console.error('Error synchronizing data:', error);
     }
 }

 synchronizeData();

Handle Conflicts: During synchronization, conflicts may arise if the same data is modified in both databases concurrently. PouchDB provides conflict resolution mechanisms to handle such scenarios. By implementing a conflict handler, we can define rules for resolving conflicts.
```
 pouchDB.replication.on('error', function (err) {
     if (err.name === 'conflict') {
         // Resolve conflict here
     }
 });
```
Offline Support: PouchDB provides built-in offline support, allowing users to work with data even when there is no network connection. Changes made offline are automatically synchronized when the connection is restored.
```
 const offlineEnabledDB = new PouchDB(dbName, { auto_compaction: true });
```

Conclusion

By implementing data synchronization between IndexedDB and PouchDB, we can create robust and reliable web applications that work seamlessly offline and online. This ensures data integrity and a smooth user experience. With the four steps outlined above, you can start building offline-first applications with confidence.

#webdevelopment #databases