mongo-oplog

library2.1.4jsnpmunverified

Watch MongoDB oplog (replica set operation log) for real-time changes in Node.js. Version 2.1.4 supports Promise/async-await, event-based streaming using eventemitter3, and filtering by namespace (database/collection). Requires MongoDB replica set configuration. Built on the native MongoDB driver. Breaking changes in 2.x dropped old callback API in favor of promises. Differentiators: lightweight, small footprint, backward-compatible callbacks in v2, and strong readability with XO.

database

npm install mongo-oplog

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · MONGO-OPLOG

mongo-oplog

databasejavascriptv2.1.4

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

default

✓ import MongoOplog from 'mongo-oplog'

✗ const { default: MongoOplog } = require('mongo-oplog')

Default ES module export since v2. Do not destructure a named export.

MongoOplog

✓ const MongoOplog = require('mongo-oplog')

✗ const { MongoOplog } = require('mongo-oplog')

CommonJS yields a function (not an object with MongoOplog property) since v2.

types

✓ import type { OplogEvent } from 'mongo-oplog'

✗ import { OplogEvent } from 'mongo-oplog'

Package ships TypeScript declarations since v2.1.0. Use 'import type' for type-only imports.

Initialize mongo-oplog, start tailing the oplog, and listen for insert/update/delete events. Stop after 10 seconds.

import MongoOplog from 'mongo-oplog'; const uri = process.env.MONGO_URI || 'mongodb://127.0.0.1:27017/local'; const options = { ns: 'test.posts' }; const oplog = MongoOplog(uri, options); oplog.tail() .then(() => console.log('Tailing started')) .catch(err => console.error('Failed to tail:', err)); oplog.on('insert', (doc) => { console.log('Inserted:', doc); }); oplog.on('update', (doc) => { console.log('Updated:', doc); }); oplog.on('delete', (doc) => { console.log('Deleted:', doc.o._id); }); oplog.on('error', (err) => { console.error('Oplog error:', err); }); // Stop after 10 seconds setTimeout(() => { oplog.stop().then(() => console.log('Stopped')); }, 10000);

Debug

Known issues

breakingVersion 2.x removed callback API; use promises or async/await

fix

Replace callbacks with .then()/await; see UPGRADE.md

affects: >=2.0.0 <2.0.0

gotchaMongoDB must be configured as a replica set; standalone mode has no oplog

fix

Start mongod with --replSet rs0 and run rs.initiate() in mongo shell

affects: >=0.0.0

deprecatedNode.js v6 and v7 support is deprecated; use Node >= 8

fix

Upgrade Node.js to 8+ or use v1.x

affects: >=2.0.0 <2.1.0

gotchaNamespace option ns must match exactly 'database.collection' pattern

fix

Use 'dbName.collectionName' (case-sensitive) or regex string like '/test.posts/'

affects: >=0.0.0

deprecatedDirect connection to a mongod without replica set name may cause silent failures

fix

Ensure connection string includes replicaSet=rs0 or use an existing replica set member

affects: >=2.0.0

Errors

Common errors & fixes

MongoError: not master and slaveOk=false

Connection to a secondary replica set member without slaveOk flag

fix

Add ?slaveOk=true to the URI or set options.slaveOk: true

AssertionError: The uri must include a valid replica set name

MongoDB driver requires replica set name when connecting to multiple hosts

fix

Add ?replicaSet=rs0 to the URI

TypeError: oplog.tail is not a function

Importing wrong export (named instead of default)

fix

Use import MongoOplog from 'mongo-oplog' (default import)

MongoError: no such cmd: 'getLog'

Connecting to MongoDB standalone instance without oplog

fix

Start MongoDB with --replSet and run rs.initiate()

Upgrade

Version history

2.1.4latest on npm

Audit

Dependencies

mongodbrequiredNative MongoDB driver for connecting and querying oplog

debugrequiredFor debugging logs

eventemitter3requiredHigh-performance event emitter for streaming events

Agent activity

4 hits · last 30 days

node

Resources

githubgit://github.com/cayasso/mongo-oplog ↗

packagemongo-oplog ↗

homepagehttps://github.com/cayasso/mongo-oplog ↗