Mongoose Close Connection

Question

I have A Mongoose Connection and at some point in my program I need to close it. after logging the mongoose object several times, I have found that the following workd

mongoose.connection.base.connections[1].close();

Is There A Cleaner way to do this?

JohnnyHK · Accepted Answer · 2018-03-01T16:20:39.993

48

To close all connections in the Mongoose connection pool:

mongoose.disconnect();

Docs here.

edited Mar 01 '18 at 16:20

answered Apr 14 '13 at 15:25

JohnnyHK

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Being new to Mongoose; when/where should I use mongoose.disconnect();? – David J Barnes Feb 19 '15 at 18:05
1

@DavidJBarnes Typically, you'll only need to call this when closing your app. – JohnnyHK Mar 07 '16 at 14:18
disconnect method not found in doc any more. – Chris Mar 01 '18 at 15:31
@Chris I updated the docs link; the new docs are incomplete so I've linked to the 4.x docs. – JohnnyHK Mar 01 '18 at 16:21
@JohnnyHK Do you have any idea why there is no doc about this method in the v5.x? – Chris Mar 02 '18 at 06:16
@JohnnyHK what does it mean when closing the app, do you mean when calling process.exit() ? – EugenSunic Oct 21 '18 at 14:55
@eugensunic No, it would be in a controlled shutdown case where your code ensures all async ops have completed before closing connections and allowing the program to terminate normally. – JohnnyHK Oct 21 '18 at 15:40

score 0 · Answer 2 · answered Jun 28 '22 at 18:47

I used a singleton in my code.

Exporting a promise

In one file I export a promise...

connection.js

const { createConnection } = require('mongoose');

function getConnection() {
  return mongoose.createConnection(...).asPromise();
}
const connPromise = getConnection();
module.exports = connPromise;

other files...

const connPromise = require('./connection.js');

async function handler() {
  // Connection starts on first module import
  // This gets faster when the connection is done being created
  const connection = await connPromise;
  // Do stuff with the connection
  return {
    data: '',
    and: '',
    stuff: '',
  };
}

When everything is shutting down, like in a lambda, also in connection.js:

process.on('SIGTERM', async () => {
  console.info('[runtime] SIGTERM received');
  const conn = await connPromise;
  await conn.close();
  console.info('[runtime] closed connection');
  process.exit(0);
});

So by storing the connection in a promise, I can get it everywhere. I don't export the connection itself because getting it is async.

Exporting a getter function

I could have a function like

let connection = null;
function getConnection() {
  if (!connection) {
    connection = await createConnection(...).asPromise();
  }
  return connection;
}

module.exports = getConnection;

other files...

const getConnection = require('./connection.js');

async function handler() {
  // Gets faster after the first call.
  // connection created on first call.
  const connection = await getConnection();
  // Do stuff with the connection
  return {
    data: '',
    and: '',
    stuff: '',
  };
}

Then your shutdown would become

process.on('SIGTERM', async () => {
  console.info('[runtime] SIGTERM received');
  if (connection) {
    await connection.close();
    console.info('[runtime] closed connection');
  }
  process.exit(0);
});

Summary

Overall, I like exporting the promise, since in every lambda function, I'm always using the database.

Since the exported promise means that the connection starts as soon as the module is imported, it's ready to go sooner than if I waited till the invocation of the getConnection() in an event handler.

For having only one connection, this is a good way to get ahold of it.

Mongoose Close Connection

2 Answers2

Exporting a promise

Exporting a getter function

Summary

Linked