express-session
Installation
$ npm install express-session
API
var session = require('express-session')
session(options)
Create a session middleware with the given options
.
Note Session data is not saved in the cookie itself, just the session ID. Session data is stored server-side.
Note Since version 1.5.0, the cookie-parser
middleware
no longer needs to be used for this module to work. This module now directly reads
and writes cookies on req
/res
. Using cookie-parser
may result in issues
if the secret
is not the same between this module and cookie-parser
.
Warning The default server-side session storage, MemoryStore
, is purposely
not designed for a production environment. It will leak memory under most
conditions, does not scale past a single process, and is meant for debugging and
developing.
For a list of stores, see compatible session stores.
Options
express-session
accepts these properties in the options object.
cookie
Settings object for the session ID cookie. The default value is
{ path: '/', httpOnly: true, secure: false, maxAge: null }
.
The following are options that can be set in this object.
domain
Specifies the value for the Domain
Set-Cookie
attribute. By default, no domain
is set, and most clients will consider the cookie to apply to only the current
domain.
expires
Specifies the Date
object to be the value for the Expires
Set-Cookie
attribute.
By default, no expiration is set, and most clients will consider this a
"non-persistent cookie" and will delete it on a condition like exiting a web browser
application.
Note If both expires
and maxAge
are set in the options, then the last one
defined in the object is what is used.
Note The expires
option should not be set directly; instead only use the maxAge
option.
httpOnly
Specifies the boolean
value for the HttpOnly
Set-Cookie
attribute. When truthy,
the HttpOnly
attribute is set, otherwise it is not. By default, the HttpOnly
attribute is set.
Note be careful when setting this to true
, as compliant clients will not allow
client-side JavaScript to see the cookie in document.cookie
.
maxAge
Specifies the number
(in milliseconds) to use when calculating the Expires
Set-Cookie
attribute. This is done by taking the current server time and adding
maxAge
milliseconds to the value to calculate an Expires
datetime. By default,
no maximum age is set.
Note If both expires
and maxAge
are set in the options, then the last one
defined in the object is what is used.
path
Specifies the value for the Path
Set-Cookie
. By default, this is set to '/'
, which
is the root path of the domain.
sameSite
Specifies the boolean
or string
to be the value for the SameSite
Set-Cookie
attribute.
true
will set theSameSite
attribute toStrict
for strict same site enforcement.false
will not set theSameSite
attribute.'lax'
will set theSameSite
attribute toLax
for lax same site enforcement.'strict'
will set theSameSite
attribute toStrict
for strict same site enforcement.
More information about the different enforcement levels can be found in the specification https://tools.ietf.org/html/draft-west-first-party-cookies-07#section-4.1.1
Note This is an attribute that has not yet been fully standardized, and may change in the future. This also means many clients may ignore this attribute until they understand it.
secure
Specifies the boolean
value for the Secure
Set-Cookie
attribute. When truthy,
the Secure
attribute is set, otherwise it is not. By default, the Secure
attribute is not set.
Note be careful when setting this to true
, as compliant clients will not send
the cookie back to the server in the future if the browser does not have an HTTPS
connection.
Please note that secure: true
is a recommended option. However, it requires
an https-enabled website, i.e., HTTPS is necessary for secure cookies. If secure
is set, and you access your site over HTTP, the cookie will not be set. If you
have your node.js behind a proxy and are using secure: true
, you need to set
"trust proxy" in express:
var app = express()
app.set('trust proxy', 1) // trust first proxy
app.use(session({
secret: 'keyboard cat',
resave: false,
saveUninitialized: true,
cookie: { secure: true }
}))
For using secure cookies in production, but allowing for testing in development,
the following is an example of enabling this setup based on NODE_ENV
in express:
var app = express()
var sess = {
secret: 'keyboard cat',
cookie: {}
}
if (app.get('env') === 'production') {
app.set('trust proxy', 1) // trust first proxy
sess.cookie.secure = true // serve secure cookies
}
app.use(session(sess))
The cookie.secure
option can also be set to the special value 'auto'
to have
this setting automatically match the determined security of the connection. Be
careful when using this setting if the site is available both as HTTP and HTTPS,
as once the cookie is set on HTTPS, it will no longer be visible over HTTP. This
is useful when the Express "trust proxy"
setting is properly setup to simplify
development vs production configuration.
genid
Function to call to generate a new session ID. Provide a function that returns
a string that will be used as a session ID. The function is given req
as the
first argument if you want to use some value attached to req
when generating
the ID.
The default value is a function which uses the uid-safe
library to generate IDs.
NOTE be careful to generate unique IDs so your sessions do not conflict.
app.use(session({
genid: function(req) {
return genuuid() // use UUIDs for session IDs
},
secret: 'keyboard cat'
}))
name
The name of the session ID cookie to set in the response (and read from in the request).
The default value is 'connect.sid'
.
Note if you have multiple apps running on the same hostname (this is just
the name, i.e. localhost
or 127.0.0.1
; different schemes and ports do not
name a different hostname), then you need to separate the session cookies from
each other. The simplest method is to simply set different name
s per app.
proxy
Trust the reverse proxy when setting secure cookies (via the "X-Forwarded-Proto" header).
The default value is undefined
.
true
The "X-Forwarded-Proto" header will be used.false
All headers are ignored and the connection is considered secure only if there is a direct TLS/SSL connection.undefined
Uses the "trust proxy" setting from express
resave
Forces the session to be saved back to the session store, even if the session was never modified during the request. Depending on your store this may be necessary, but it can also create race conditions where a client makes two parallel requests to your server and changes made to the session in one request may get overwritten when the other request ends, even if it made no changes (this behavior also depends on what store you're using).
The default value is true
, but using the default has been deprecated,
as the default will change in the future. Please research into this setting
and choose what is appropriate to your use-case. Typically, you'll want
false
.
How do I know if this is necessary for my store? The best way to know is to
check with your store if it implements the touch
method. If it does, then
you can safely set resave: false
. If it does not implement the touch
method and your store sets an expiration date on stored sessions, then you
likely need resave: true
.
rolling
Force a session identifier cookie to be set on every response. The expiration
is reset to the original maxAge
, resetting the expiration
countdown.
The default value is false
.
Note When this option is set to true
but the saveUninitialized
option is
set to false
, the cookie will not be set on a response with an uninitialized
session.
saveUninitialized
Forces a session that is "uninitialized" to be saved to the store. A session is
uninitialized when it is new but not modified. Choosing false
is useful for
implementing login sessions, reducing server storage usage, or complying with
laws that require permission before setting a cookie. Choosing false
will also
help with race conditions where a client makes multiple parallel requests
without a session.
The default value is true
, but using the default has been deprecated, as the
default will change in the future. Please research into this setting and
choose what is appropriate to your use-case.
Note if you are using Session in conjunction with PassportJS, Passport will add an empty Passport object to the session for use after a user is authenticated, which will be treated as a modification to the session, causing it to be saved. This has been fixed in PassportJS 0.3.0
secret
Required option
This is the secret used to sign the session ID cookie. This can be either a string for a single secret, or an array of multiple secrets. If an array of secrets is provided, only the first element will be used to sign the session ID cookie, while all the elements will be considered when verifying the signature in requests.
store
The session store instance, defaults to a new MemoryStore
instance.
unset
Control the result of unsetting req.session
(through delete
, setting to null
,
etc.).
The default value is 'keep'
.
'destroy'
The session will be destroyed (deleted) when the response ends.'keep'
The session in the store will be kept, but modifications made during the request are ignored and not saved.
req.session
To store or access session data, simply use the request property req.session
,
which is (generally) serialized as JSON by the store, so nested objects
are typically fine. For example below is a user-specific view counter:
// Use the session middleware
app.use(session({ secret: 'keyboard cat', cookie: { maxAge: 60000 }}))
// Access the session as req.session
app.get('/', function(req, res, next) {
var sess = req.session
if (sess.views) {
sess.views++
res.setHeader('Content-Type', 'text/html')
res.write('<p>views: ' + sess.views + '</p>')
res.write('<p>expires in: ' + (sess.cookie.maxAge / 1000) + 's</p>')
res.end()
} else {
sess.views = 1
res.end('welcome to the session demo. refresh!')
}
})
Session.regenerate()
To regenerate the session simply invoke the method. Once complete,
a new SID and Session
instance will be initialized at req.session
.
req.session.regenerate(function(err) {
// will have a new session here
})
Session.destroy()
Destroys the session, removing req.session
; will be re-generated next request.
req.session.destroy(function(err) {
// cannot access session here
})
Session.reload()
Reloads the session data.
req.session.reload(function(err) {
// session updated
})
Session.save()
Save the session back to the store, replacing the contents on the store with the contents in memory (though a store may do something else--consult the store's documentation for exact behavior).
This method is automatically called at the end of the HTTP response if the session data has been altered (though this behavior can be altered with various options in the middleware constructor). Because of this, typically this method does not need to be called.
There are some cases where it is useful to call this method, for example, long- lived requests or in WebSockets.
req.session.save(function(err) {
// session saved
})
Session.touch()
Updates the .maxAge
property. Typically this is
not necessary to call, as the session middleware does this for you.
req.session.id
Each session has a unique ID associated with it. This property will contain the session ID and cannot be modified.
req.session.cookie
Each session has a unique cookie object accompany it. This allows
you to alter the session cookie per visitor. For example we can
set req.session.cookie.expires
to false
to enable the cookie
to remain for only the duration of the user-agent.
Cookie.maxAge
Alternatively req.session.cookie.maxAge
will return the time
remaining in milliseconds, which we may also re-assign a new value
to adjust the .expires
property appropriately. The following
are essentially equivalent
var hour = 3600000
req.session.cookie.expires = new Date(Date.now() + hour)
req.session.cookie.maxAge = hour
For example when maxAge
is set to 60000
(one minute), and 30 seconds
has elapsed it will return 30000
until the current request has completed,
at which time req.session.touch()
is called to reset req.session.maxAge
to its original value.
req.session.cookie.maxAge // => 30000
req.sessionID
To get the ID of the loaded session, access the request property
req.sessionID
. This is simply a read-only value set when a session
is loaded/created.
Session Store Implementation
Every session store must be an EventEmitter
and implement specific
methods. The following methods are the list of required, recommended,
and optional.
- Required methods are ones that this module will always call on the store.
- Recommended methods are ones that this module will call on the store if available.
- Optional methods are ones this module does not call at all, but helps present uniform stores to users.
For an example implementation view the connect-redis repo.
store.all(callback)
Optional
This optional method is used to get all sessions in the store as an array. The
callback
should be called as callback(error, sessions)
.
store.destroy(sid, callback)
Required
This required method is used to destroy/delete a session from the store given
a session ID (sid
). The callback
should be called as callback(error)
once
the session is destroyed.
store.clear(callback)
Optional
This optional method is used to delete all sessions from the store. The
callback
should be called as callback(error)
once the store is cleared.
store.length(callback)
Optional
This optional method is used to get the count of all sessions in the store.
The callback
should be called as callback(error, len)
.
store.get(sid, callback)
Required
This required method is used to get a session from the store given a session
ID (sid
). The callback
should be called as callback(error, session)
.
The session
argument should be a session if found, otherwise null
or
undefined
if the session was not found (and there was no error). A special
case is made when error.code === 'ENOENT'
to act like callback(null, null)
.
store.set(sid, session, callback)
Required
This required method is used to upsert a session into the store given a
session ID (sid
) and session (session
) object. The callback should be
called as callback(error)
once the session has been set in the store.
store.touch(sid, session, callback)
Recommended
This recommended method is used to "touch" a given session given a
session ID (sid
) and session (session
) object. The callback
should be
called as callback(error)
once the session has been touched.
This is primarily used when the store will automatically delete idle sessions and this method is used to signal to the store the given session is active, potentially resetting the idle timer.
Compatible Session Stores
The following modules implement a session store that is compatible with this module. Please make a PR to add additional modules :)
cassandra-store An Apache Cassandra-based session store.
cluster-store A wrapper for using in-process / embedded
stores - such as SQLite (via knex), leveldb, files, or memory - with node cluster (desirable for Raspberry Pi 2
and other multi-core embedded devices).
connect-azuretables An Azure Table Storage-based session store.
connect-couchbase A couchbase-based session store.
connect-dynamodb A DynamoDB-based session store.
connect-mssql A SQL Server-based session store.
connect-monetdb A MonetDB-based session store.
connect-mongo A MongoDB-based session store.
connect-mongodb-session Lightweight MongoDB-based session store built and maintained by MongoDB.
connect-pg-simple A PostgreSQL-based session store.
connect-redis A Redis-based session store.
connect-memcached A memcached-based session store.
connect-session-knex A session store using
Knex.js, which is a SQL query builder for PostgreSQL, MySQL, MariaDB, SQLite3, and Oracle.
connect-session-sequelize A session store using
Sequelize.js, which is a Node.js / io.js ORM for PostgreSQL, MySQL, SQLite and MSSQL.
express-mysql-session A session store using native
MySQL via the node-mysql module.
connect-sqlite3 A SQLite3 session store modeled after the TJ's
connect-redis
store.
express-nedb-session A NeDB-based session store.
level-session-store A LevelDB-based session store.
mssql-session-store A SQL Server-based session store.
nedb-session-store An alternate NeDB-based (either in-memory or file-persisted) session store.
sequelstore-connect A session store using Sequelize.js.
session-file-store A file system-based session store.
session-rethinkdb A RethinkDB-based session store.
Example
A simple example using express-session
to store page views for a user.
var express = require('express')
var parseurl = require('parseurl')
var session = require('express-session')
var app = express()
app.use(session({
secret: 'keyboard cat',
resave: false,
saveUninitialized: true
}))
app.use(function (req, res, next) {
var views = req.session.views
if (!views) {
views = req.session.views = {}
}
// get the url pathname
var pathname = parseurl(req).pathname
// count the views
views[pathname] = (views[pathname] || 0) + 1
next()
})
app.get('/foo', function (req, res, next) {
res.send('you viewed this page ' + req.session.views['/foo'] + ' times')
})
app.get('/bar', function (req, res, next) {
res.send('you viewed this page ' + req.session.views['/bar'] + ' times')
})