JS20 - Documentation

Transactions

The whole run() function in an Endpoint action is using a single DB transaction (one transaction per database you register). When you call any model methods inside an Endpoint, or call other actions recursively, they all run within the same transaction. If anything fails - everything is rolled back - and the API returns a 500 error.

app.addEndpoint({
    method: 'GET',
    path: '/failure-example',
    outputSchema: sMessage,
    isLoggedIn: true,
    run: async (system) => {
        // Transaction is started here automatically

        // We create some entry
        await system.models.myModel.create(...);

        // We update another entry
        await system.models.otherModel.update(...);

        // This inner action throws an error
        // -> Transaction is rolled back, nothing is saved to DB
        // -> Action throws error and returns 500 to client
        await system.run(someActionThatThrowsError);

        return {
            message: 'We never reach here',
        };
    }
});

app.addEndpoint({
    method: 'GET',
    path: '/success-example',
    outputSchema: sMessage,
    isLoggedIn: true,
    run: async (system) => {
        // Transaction is started here automatically

        // We create some entry
        await system.models.myModel.create(...);

        // We update another entry
        await system.models.otherModel.update(...);

        // This inner action works fine
        await system.run(someActionThatWorksFine);

        return {
            message: 'All went well!',
        };

        // -> Transaction is commited here, all changes are saved to DB
        // -> User gets 200 Ok
    }
});

What's happening here?

• All endpoint actions are wrapped in DB transactions automatically.
• Calling create(), update() & delete() will use the transaction.
• Calling other actions with system.run() will use the same transaction.
• If any error is thrown, the transaction is rolled back.
• If everything works fine, the transaction is committed.
• Only at the end of the endpoint action will anything actually be saved to the DB.