Listening to MongoDB live changes using oplog.
- Support start and stop tailing the MongoDB
oplog
at any time. - Support filtering
oplog
events bynamespaces
(database and collections). - Built on top of the native NodeJS MongoDB driver.
Promise
support which enables the use ofasync
andawait
.- The package has a very small footprint and requires just a few dependencies, including
mongodb
andeventemitter3
. - Uses
eventemitter3
for high performance event emitting. - Unit tested with
mocha
and built withtypescript
so bundled types are always up to date. - Differences from mongo-oplog
- does not attempt to support older versions of NodeJS; output Javascript targets
es2016
- does not have callback support for oplog operations (tail, stop, etc.)
- built with
typescript
- use
new
to create an instance ofMongoOplog
or you can use the default export ofcreateInstance
which will do this for you - supports "pretty" format of emitted documents which conform to the style in mongo-trigger
- does not attempt to support older versions of NodeJS; output Javascript targets
$ npm install mongo-oplog2
import {MongoOplog, OplogDoc} from 'mongo-oplog2';
const oplog: MongoOplog = new MongoOplog('mongodb://127.0.0.1:27017/local', { ns: 'test.posts' });
oplog.tail();
oplog.on('op', (data: OplogDoc) => {
console.log(data);
});
oplog.on('insert', (doc: OplogDoc) => {
console.log(doc);
});
oplog.on('update', (doc: OplogDoc) => {
console.log(doc);
});
oplog.on('delete', (doc: OplogDoc) => {
console.log(doc.o._id);
});
oplog.on('error', (error: Error) => {
console.log(error);
});
oplog.on('end', () => {
console.log('Stream ended');
});
oplog.stop().then(() => {
console.log('server stopped');
});
uriOrDb
: Valid MongoDB uri or a MongoDB server instance.options
MongoDB connection options.
Start tailing.
This method only supports Promise
syntax.
oplog.tail().then(() => {
console.log('tailing started');
}).catch(err => console.error(err));
// or with async/await
async function tail() {
try {
await oplog.tail();
console.log('tailing started');
} catch (err) {
console.log(err);
}
}
Stop tailing and disconnect from server.
This method only supports Promise
syntax.
oplog.stop().then(() => {
console.log('tailing stopped');
}).catch(err => console.error(err));
// or with async/await
async function stop() {
try {
await oplog.stop();
console.log('tailing stopped');
} catch (err) {
console.log(err);
}
}
Destroy the mongo-oplog
object by stop tailing and disconnecting from server.
This method only supports Promise
syntax.
oplog.destroy.then(() => {
console.log('destroyed');
}).catch(err => console.error(err));
// or with async/await
async function destroy() {
try {
await oplog.destroy();
console.log('destroyed');
} catch (err) {
console.log(err);
}
}
Ignore incoming oplog events.
NOTE: This does not prevent the oplog
itself from progressing the cursor. Any updates during the time between when you start ignoring and stop ignoring will not be sent to your application. The timestamp prior to start of ignore being set is preserved. If you really want to stop receiving events and then start receiving them again without loss you must use stop
and tail
instead of simply using ignore
.
oplog.ignore = true; // to stop receiving events
oplog.ignore = false; // to resume receiving events
Create and return a filter object.
const filter = oplog.filter('*.posts');
filter.on('op', fn);
oplog.tail();
Destroy filter object.
filter.destroy();
Ignore / resume filtered events.
NOTE: Ignoring events can easily result in missed events. See above.
filter.ignore = true; // to ignore events
filter.ignore = false; // to resume recepit of events
Events supported by oplog
and filter
;
op
: All bellow operations (oplog/filter).insert
: Document insert (oplog/filter).update
: Document update (oplog/filter).delete
: Document delete (oplog/filter).end
: Cursor stream ended (oplog).error
: Error (oplog).
Configure MongoDB for active oplog:
Start MongoDB with:
$ mongod --replSet test
Start a mongo
shell and configure mongo as follows:
$ mongo
> var config = {_id: "test", members: [{_id: 0, host: "127.0.0.1:27017"}]};
> rs.initiate(config);
Once configuration is initiated then you can run the test:
$ npm install
$ npm run test
This is a port of cayasso's mongo-oplog module to typescript
, which guarantees types will always be up to date when using this package in your own TypeScript projects.
Pretty document format is compatible with mongo-trigger.
(The MIT License)
Copyright (c) 2017 Jarom Loveridge
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.