Upgrading think-mongo to Support MongoDB 4.x and Transactions in ThinkJS

The author, a former front‑end engineer at Qiwu Group, describes the motivation for upgrading the think-mongo module: MongoDB has moved from version 2.x to 4.x, introducing transactions that many developers want to use.

Because the original think-mongo depends on the legacy mongodb driver (2.x), a simple version bump is impossible; the driver’s API has changed dramatically. The upgrade therefore requires refactoring the underlying connection logic, splitting the old Db methods into separate Client and Db classes.

// previous usage MongoClient.connect('mongodb://localhost:27017/test', (err, db) => { /* ... */ }); // new usage MongoClient.connect('mongodb://localhost:27017/test', (err, client) => { const db = client.db('test'); /* ... */ });

CRUD APIs have also been refined: collection.insert() becomes insertOne() and insertMany() ; collection.remove() becomes deleteOne() and deleteMany() ; collection.update() becomes updateOne() and updateMany() ; and collection.find(where, field) is split into find(where).project(field) . The module’s own add() and addMany() map naturally to the new insertOne() / insertMany() methods.

With MongoDB 4.x the driver now supports native transactions. Unlike SQL’s START TRANSACTION / COMMIT / ROLLBACK statements, MongoDB uses a session object. Each transaction creates a session, and all CRUD operations must receive this session so they are recorded in the same transaction.

const client = new MongoClient(uri); await client.connect(); const session = client.startSession(); try { session.startTransaction(); await client.db('think_db').add({name: 'thinkjs'}, {session}); await session.commitTransaction(); } catch (e) { await session.abortTransaction(); } finally { await session.endSession(); await client.close(); }

In a ThinkJS controller the author demonstrates how to wrap multiple model operations in a transaction using the provided transaction() helper, passing the session via the model’s options.session property so that subsequent CRUD calls automatically inherit the transaction context.

module.exports = class extends think.Controller { async indexAction() { const UserModel = this.mongo('user'); const PostModel = this.mongo('post'); await UserModel.transaction(async session => { PostModel.options.session = session; const userId = await UserModel.add({name: 'lizheming'}); await PostModel.add({userId, content: 'Hello World'}); }); } };

The article concludes with a note that the upgraded [email protected] already incorporates these changes, and developers using the native mongodb driver should adjust their code according to the listed API modifications.