CODEWITHSUNDEEP
node.jsmongodbmongoose
user11810899
user11810899

Reputation:

how to handle disconnect error for MongoDB

I am seeing this uncaught exception in my Node.js process:

Uncaught exception: { Error: read ETIMEDOUT
    at TCP.onStreamRead (internal/stream_base_commons.js:162:27)
  name: 'MongoNetworkError',
  errorLabels: [ 'TransientTransactionError' ],
  [Symbol(mongoErrorContextSymbol)]: { isGetMore: true } }

I tried capturing/trapping it using:

import * as mdb from 'mongodb'
const d = new mdb.MongoClient(...);
d.on('error', () => {...});  // trap it here

but that does not seem to be able to trap the error. Anyone know how I can do so?

Upvotes: 3

Views: 1526

Answers (4)

rafathasan
rafathasan

Reputation: 572

Use monk for the problem. I had faced the same problem a year ago but the monk saved me.

Here is a Example

const monk = require('monk')
const db = monk()

db.on('timeout', () => {
  console.log('Mongo connection lost')
})

db.on('close', () => {
  console.log('Mongo connection closed')
})

db.on('reconnect', () => {
  console.log('Mongo reconnected')
})

db._db.on('timeout', () => {
  console.log('Mongo connection lost')
})

db._db.on('close', () => {
  console.log('Mongo connection closed')
})

db._db.on('reconnect', () => {
  console.log('Mongo reconnected')
})

Upvotes: 0

vkarpov15
vkarpov15

Reputation: 3872

There are 2 distinct types of connection errors when using the MongoDB driver:

  1. Errors during initial connection
  2. Errors after initial connection is established

The 'error' event is used to handle (2). It looks like you're looking for the correct way to handle initial connection errors. For those, you should either pass a callback to connect() or .catch() on the promise that connect() returns.

const NUM_RETRIES = 3;
const delay = 1000;
let error = null;
for (let i = 0; i < NUM_RETRIES; ++i) {
  if (i > 0) {
    await new Promise(resolve => setTimeout(resolve, i * delay));
  }
  try {
    await mdb.MongoClient.connect(uri);
    break;
  } catch (err) {
    error = err;
  }
}

Upvotes: 2

Ilijanovic
Ilijanovic

Reputation: 14914

Well you can try it out with d.connect:

import * as mdb from 'mongodb'
const d = new mdb.MongoClient(...);
d.connect("your url").then().catch(err => {
      console.log(err)
})

Upvotes: 0

ktilcu
ktilcu

Reputation: 3128

The client doesn't emit events. The DB does. Get access to the db with client.db(dbName)

import * as mdb from 'mongodb'
const d = new mdb.MongoClient(url, options, function (err, client) {
  if (err) //do something
  const d = client.db(dbName);
  // available events: close,error,fullsetup,parseError,reconnect,timeout
  d.on('timeout', () => {...});  // trap it here
});

Upvotes: 0

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