V4 migration guide

To migrate the library from V3 to V4, re-install the dependencies.

Use your package manager (npm example shown):

npm uninstall connect-mongo
npm uninstall @types/connect-mongo
npm install connect-mongo

Next step is to import the dependencies

Javascript:

const MongoStore = require('connect-mongo');

Typescript:

import MongoStore from 'connect-mongo';

Create the store using MongoStore.create(options) instead of new MongoStore(options)

app.use(session({
  secret: 'foo',
  store: MongoStore.create(options)
}));

For the options, you should make the following changes:

Change url to mongoUrl
Change collection to collectionName if you are using it
Keep clientPromise if you are using it
mongooseConnection has been removed. Please update your application code to use either mongoUrl, client or clientPromise
To reuse an existing mongoose connection retreive the mongoDb driver from you mongoose connection using Connection.prototype.getClient() and pass it to the store in the client-option.
Remove fallbackMemory option and if you are using it, you can import from:

const session = require('express-session');

app.use(session({
  store: isDev ? new session.MemoryStore() : MongoStore.create(options)
}));

You can also take a look at example directory for example usage.

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