Session

You can manage user sessions inside your AdonisJS application using the @adonisjs/session package. The session package provides a unified API for storing session data across different storage providers.

Following is the list of the bundled stores.

cookie: The session data is stored inside an encrypted cookie. The cookie store works great with multi-server deployments since the data is stored with the client.
file: The session data is saved inside a file on the server. The file store can only scale to multi-server deployments if you implement sticky sessions with the load balancer.
redis: The session data is stored inside a Redis database. The redis store is recommended for apps with large volumes of session data and can scale to multi-server deployments.
memory: The session data is stored within a global memory store. The memory store is used during testing.

Alongside the inbuilt backend stores, you can also create and register custom session stores.

Installation

Install and configure the package using the following command :

node ace add @adonisjs/session

Installs the @adonisjs/session package using the detected package manager.

Registers the following service provider inside the adonisrc.ts file.

{
  providers: [
    // ...other providers
    () => import('@adonisjs/session/session_provider')
  ]
}

Create the config/session.ts file.
Define the following environment variables and their validations.
```
SESSION_DRIVER=cookie
```
Registers the following middleware inside the start/kernel.ts file.
```
router.use([
  () => import('@adonisjs/session/session_middleware')
])
```

Configuration

The configuration for the session package is stored inside the config/session.ts file.

Stores configuration

Following is the list of the backend stores bundled with the @adonisjs/session package.

import app from '@adonisjs/core/services/app'
import { defineConfig, stores } from '@adonisjs/session'

export default defineConfig({
  store: env.get('SESSION_DRIVER'),

  stores: {
    cookie: stores.cookie(),

    file: stores.file({
      location: app.tmpPath('sessions')
    }),

    redis: stores.redis({
      connection: 'main'
    })
  }
})

stores.cookie

The cookie store encrypts and stores the session data inside a cookie.

stores.file

Define the configuration for the file store. The method accepts the location path for storing the session files.

stores.redis

Define the configuration for the redis store. The method accepts the connection name for storing the session data.

Make sure to first install and configure the @adonisjs/redis package before using the redis store.

Updating environment variables validation

If you decide to use session stores other than the default one, make sure to also update the environment variables validation for the SESSION_DRIVER environment variable.

We configure the cookie and the redis stores in the following example. Therefore, we should also allow the SESSION_DRIVER environment variable to be one of them.

import { defineConfig, stores } from '@adonisjs/session'

export default defineConfig({
  store: env.get('SESSION_DRIVER'),

  stores: {
    cookie: stores.cookie(),
    redis: stores.redis({
      connection: 'main'
    })
  }
})

start/env.ts

{
  SESSION_DRIVER: Env.schema.enum(['cookie', 'redis', 'memory'] as const)
}

Basic example

Once the session package has been registered, you can access the session property from the HTTP Context. The session property exposes the API for reading and writing data to the session store.

import router from '@adonisjs/core/services/router'

router.get('/theme/:color', async ({ params, session, response }) => {
  session.put('theme', params.color)
  response.redirect('/')
})

router.get('/', async ({ session }) => {
  const colorTheme = session.get('theme')
  return `You are using ${colorTheme} color theme`
})

The session data is read from the session store at the start of the request and written back to the store at the end. Therefore, all changes are kept in memory until the request finishes.

Supported data types

The session data is serialized to a string using JSON.stringify; therefore, you can use the following JavaScript data types as session values.

string
number
bigInt
boolean
null
object
array

// Object
session.put('user', {
  id: 1,
  fullName: 'virk',
})

// Array
session.put('product_ids', [1, 2, 3, 4])

// Boolean
session.put('is_logged_in', true)

// Number
session.put('visits', 10)

// BigInt
session.put('visits', BigInt(10))

// Data objects are converted to ISO string
session.put('visited_at', new Date())

Reading and writing data

Following is the list of methods you can access from the session object to interact with the data.

get

Returns the value of a key from the store. You can use dot notation to read nested values.

session.get('key')
session.get('user.email')

You can also define a default value as the second parameter. The default value will be returned if the key does not exist in the store.

session.get('visits', 0)

has

Check if a key exists in the session store.

if (session.has('visits')) {
}

all

Returns all the data from the session store. The return value will always be an object.

session.all()

put

Add a key-value pair to the session store. You can create objects with nested values using the dot notation.

session.put('user', { email: 'foo@bar.com' })

// Same as above
session.put('user.email', 'foo@bar.com')

forget

Remove a key-value pair from the session store.

session.forget('user')

// Remove the email from the user object
session.forget('user.email')

pull

The pull method returns the value of a key and removes it from the store simultaneously.

const user = session.pull('user')
session.has('user') // false

increment

The increment method increments the value of a key. A new key value is defined if it does not exist already.

session.increment('visits')

// Increment by 4
session.increment('visits', 4)

decrement

The decrement method decrements the value of a key. A new key value is defined if it does not exist already.

session.decrement('visits')

// Decrement by 4
session.decrement('visits', 4)

clear

The clear method removes everything from the session store.

session.clear()

Session lifecycle

AdonisJS creates an empty session store and assigns it to a unique session ID on the first HTTP request, even if the request/response lifecycle doesn't interact with sessions.

On every subsequent request, we update the maxAge property of the session ID cookie to ensure it doesn't expire. Also, the session store is notified about the changes (if any) to update and persist the changes.

You can access the unique session ID using the sessionId property. The session ID for a visitor remains the same until it expires.

console.log(session.sessionId)

Re-generating session id

Re-generating session ID helps prevent a session fixation attack in your application. You must re-generate the session ID when associating an anonymous session with a logged-in user.

The @adonisjs/auth package re-generates the session ID automatically; therefore, you do not have to do it manually.

/**
 * New session ID will be assigned at
 * the end of the request
 */
session.regenerate()

Flash messages

Flash messages are used to pass data between two HTTP requests. They are commonly used to provide feedback to the user after a specific action. For example, showing the success message after the form submission or displaying the validation error messages.

In the following example, we define the routes for displaying the contact form and submitting the form details to the database. Post form submission, we redirect the user back to the form alongside a success notification using flash messages.

import router from '@adonisjs/core/services/router'

router.post('/contact', ({ session, request, response }) => {
  const data = request.all()
  // Save contact data
  
  session.flash('notification', {
    type: 'success',
    message: 'Thanks for contacting. We will get back to you'
  })

  response.redirect().back()
})

router.get('/contact', ({ view }) => {
  return view.render('contact')
})

You can access the flash messages inside the edge templates using the flashMessage tag or the flashMessages property.

@flashMessage('notification')
  <div class="notification {{ $message.type }}">
    {{ $message.message }}
  </div>
@end

<form method="POST" action="/contact">
  <!-- Rest of the form -->
</form>

You can access the flash messages inside controllers using the session.flashMessages property.

router.get('/contact', ({ view, session }) => {
  console.log(session.flashMessages.all())
  return view.render('contact')
})

Validation errors and flash messages

The Session middleware automatically captures the validation exceptions and redirects the user back to the form. The validation errors and form input data are kept within flash messages, and you can access them inside Edge templates.

In the following example:

We access the value of the title input field using the old method.
And access the error message using the @inputError tag.

<form method="POST" action="/posts">
  <div>
    <label for="title"> Title </label>
    <input 
      type="text"
      id="title"
      name="title"
      value="{{ old('title') || '' }}"
    />

    @inputError('title')
      @each(message in $messages)
        <p> {{ message }} </p>
      @end
    @end
  </div>
</form>

Writing flash messages

The following are the methods to write data to the flash messages store. The session.flash method accepts a key-value pair and writes it to the flash messages property inside the session store.

session.flash('key', value)
session.flash({
  key: value
})

Instead of manually reading the request data and storing it in the flash messages, you can use one of the following methods to flash form data.

flashAll

/**
 * Short hand for flashing request
 * data
 */
session.flashAll()

/**
 * Same as "flashAll"
 */
session.flash(request.all())

flashOnly

/**
 * Short hand for flashing selected 
 * properties from request data
 */
session.flashOnly(['username', 'email'])

/**
 * Same as "flashOnly"
 */
session.flash(request.only(['username', 'email']))

flashExcept

/**
 * Short hand for flashing selected 
 * properties from request data
 */
session.flashExcept(['password'])

/**
 * Same as "flashExcept"
 */
session.flash(request.except(['password']))

Finally, if you want to reflash the current flash messages, you can do that using the session.reflash method.

session.reflash()
session.reflashOnly(['notification', 'errors'])
session.reflashExcept(['errors'])

Reading flash messages

The flash messages are only available in the subsequent request after the redirect. You can access them using the session.flashMessages property.

console.log(session.flashMessages.all())
console.log(session.flashMessages.get('key'))
console.log(session.flashMessages.has('key'))

The same flashMessages property is also shared with Edge templates, and you can access it as follows.

Events

Please check the events reference guide to view the list of events dispatched by the @adonisjs/session package.

Creating a custom session store

Session stores must implement the SessionStoreContract interface and define the following methods.

import {
  SessionData,
  SessionStoreFactory,
  SessionStoreContract,
} from '@adonisjs/session/types'

/**
 * The config you want to accept
 */
export type MongoDBConfig = {}

/**
 * Driver implementation
 */
export class MongoDBStore implements SessionStoreContract {
  constructor(public config: MongoDBConfig) {
  }

  /**
   * Returns the session data for a session ID. The method
   * must return null or an object of a key-value pair
   */
  async read(sessionId: string): Promise<SessionData | null> {
  }

  /**
   * Save the session data against the provided session ID
   */
  async write(sessionId: string, data: SessionData): Promise<void> {
  }

  /**
   * Delete session data for the given session ID
   */
  async destroy(sessionId: string): Promise<void> {
  }

  /**
   * Reset the session expiry
   */
  async touch(sessionId: string): Promise<void> {
  }
}

/**
 * Factory function to reference the store
 * inside the config file.
 */
export function mongoDbStore (config: MongoDbConfig): SessionStoreFactory {
  return (ctx, sessionConfig) => {
    return new MongoDBStore(config)
  }
}

In the above code example, we export the following values.

MongoDBConfig: TypeScript type for the configuration you want to accept.
MongoDBStore: The store's implementation as a class. It must adhere to the SessionStoreContract interface.
mongoDbStore: Finally, a factory function to create an instance of the store for every HTTP request.

Using the store

Once the store has been created, you can reference it inside the config file using the mongoDbStore factory function.

config/session.ts

import { defineConfig } from '@adonisjs/session'
import { mongDbStore } from 'my-custom-package'

export default defineConfig({
  stores: {
    mongodb: mongoDbStore({
      // config goes here
    })
  }
})

A note on serializing data

The write method receives the session data as an object, and you might have to convert it to a string before saving it. You can use any serialization package for the same or the MessageBuilder helper provided by the AdonisJS helpers module. For inspiration, please consult the official session stores.