如何在 node.js 和 mongoDB 本机驱动程序上启用调试？

Question

i use node.js and node-mongodb-native driver, with connection pooling. is there any way to enable debug for see what's happening, how many connections are active and when a connection is opened or closed?

i would like to see something like:

* connection xxx opened on host:port
* connection yyy opened on host:port
* connection xxx closed

Answer 1

1. To watch the commands been sent to MongoDB, set the driver logger's level to debug .
2. To react to connection pool events , just subscribe to them and log yourself.
3. You may need the topology monitoring to react to changes of topology, such as joins to a secondary or disconnections with a replica set.

const client = new MongoClient('mongodb://127.0.0.1:27017/', {
  useUnifiedTopology: true,
  loggerLevel: 'debug',
  // logger: (message, context) => console.dir(context),
})

// connection pool monitoring
client.on('connectionPoolCreated', event => console.dir(event))
client.on('connectionPoolClosed', event => console.dir(event))
client.on('connectionCreated', event => console.dir(event))
client.on('connectionReady', event => console.dir(event))
client.on('connectionClosed', event => console.dir(event))
client.on('connectionCheckOutStarted', event => console.dir(event))
client.on('connectionCheckOutFailed', event => console.dir(event))
client.on('connectionCheckedOut', event => console.dir(event))
client.on('connectionCheckedIn', event => console.dir(event))
client.on('connectionPoolCleared', event => console.dir(event))

// topology monitoring
client.on('serverDescriptionChanged', event => console.dir(event))
client.on('serverHeartbeatStarted', event => console.dir(event))
client.on('serverHeartbeatSucceeded', event => console.dir(event))
client.on('serverHeartbeatFailed', event => console.dir(event))
client.on('serverOpening', event => console.dir(event))
client.on('serverClosed', event => console.dir(event))
client.on('topologyOpening', event => console.dir(event))
client.on('topologyClosed', event => console.dir(event))
client.on('topologyDescriptionChanged', event => console.dir(event))

Answer 2

The Db() and Server() objects both support a logger option, which is an object with log , error and debug functions. The Db() option doesn't appear to be documented at the moment, but it is mentioned in the 0.9.6-20 2011-10-04 changelog entry .

I'm not sure if all of the information you need is supported with this interface, but it's definitely a good place to start. The driver team would also probably welcome a pull request to add such features.

Answer 3

You can use the node's driver Logger class:

import { Logger } from "mongodriver";

And later in your code:

Logger.setLevel("debug");

You can check documentation on the official driver API doc