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Read and write data to cookies through ActionController::Cookies#cookies.

When reading cookie data, the data is read from the HTTP request header, Cookie. When writing cookie data, the data is sent out in the HTTP response header, Set-Cookie.

Examples of writing:

# Sets a simple session cookie.
# This cookie will be deleted when the user's browser is closed.
cookies[:user_name] = "david"

# Cookie values are String-based. Other data types need to be serialized.
cookies[:lat_lon] = JSON.generate([47.68, -122.37])

# Sets a cookie that expires in 1 hour.
cookies[:login] = { value: "XJ-122", expires: 1.hour }

# Sets a cookie that expires at a specific time.
cookies[:login] = { value: "XJ-122", expires: Time.utc(2020, 10, 15, 5) }

# Sets a signed cookie, which prevents users from tampering with its value.
# It can be read using the signed method `cookies.signed[:name]`
cookies.signed[:user_id] =

# Sets an encrypted cookie value before sending it to the client which
# prevent users from reading and tampering with its value.
# It can be read using the encrypted method `cookies.encrypted[:name]`
cookies.encrypted[:discount] = 45

# Sets a "permanent" cookie (which expires in 20 years from now).
cookies.permanent[:login] = "XJ-122"

# You can also chain these methods:
cookies.signed.permanent[:login] = "XJ-122"

Examples of reading:

cookies[:user_name]           # => "david"
cookies.size                  # => 2
JSON.parse(cookies[:lat_lon]) # => [47.68, -122.37]
cookies.signed[:login]        # => "XJ-122"
cookies.encrypted[:discount]  # => 45

Example for deleting:

cookies.delete :user_name

Please note that if you specify a :domain when setting a cookie, you must also specify the domain when deleting the cookie:

cookies[:name] = {
  value: 'a yummy cookie',
  expires: 1.year,
  domain: ''

cookies.delete(:name, domain: '')

The option symbols for setting cookies are:

  • :value - The cookie’s value.

  • :path - The path for which this cookie applies. Defaults to the root of the application.

  • :domain - The domain for which this cookie applies so you can restrict to the domain level. If you use a schema like and want to share session with set :domain to :all. To support multiple domains, provide an array, and the first domain matching will be used. Make sure to specify the :domain option with :all or Array again when deleting cookies. For more flexibility you can set the domain on a per-request basis by specifying :domain with a proc.

    domain: nil  # Does not set cookie domain. (default)
    domain: :all # Allow the cookie for the top most level
                 # domain and subdomains.
    domain: %w( # Allow the cookie
                                          # for concrete domain names.
    domain: proc { Tenant.current.cookie_domain } # Set cookie domain dynamically
    domain: proc { |req| ".sub.#{}" }     # Set cookie domain dynamically based on request
  • :tld_length - When using :domain => :all, this option can be used to explicitly set the TLD length when using a short (<= 3 character) domain that is being interpreted as part of a TLD. For example, to share cookies between and, set :tld_length to 2.

  • :expires - The time at which this cookie expires, as a Time or ActiveSupport::Duration object.

  • :secure - Whether this cookie is only transmitted to HTTPS servers. Default is false.

  • :httponly - Whether this cookie is accessible via scripting or only HTTP. Defaults to false.

  • :same_site - The value of the SameSite cookie attribute, which determines how this cookie should be restricted in cross-site contexts. Possible values are nil, :none, :lax, and :strict. Defaults to :lax.



AUTHENTICATED_ENCRYPTED_COOKIE_SALT = "action_dispatch.authenticated_encrypted_cookie_salt"
COOKIES_DIGEST = "action_dispatch.cookies_digest"
COOKIES_ROTATIONS = "action_dispatch.cookies_rotations"
COOKIES_SAME_SITE_PROTECTION = "action_dispatch.cookies_same_site_protection"
COOKIES_SERIALIZER = "action_dispatch.cookies_serializer"
CookieOverflow = StandardError

Raised when storing more than 4K of session data.

ENCRYPTED_COOKIE_CIPHER = "action_dispatch.encrypted_cookie_cipher"
ENCRYPTED_COOKIE_SALT = "action_dispatch.encrypted_cookie_salt"
ENCRYPTED_SIGNED_COOKIE_SALT = "action_dispatch.encrypted_signed_cookie_salt"
GENERATOR_KEY = "action_dispatch.key_generator"
HTTP_HEADER = "Set-Cookie"

Cookies can typically store 4096 bytes.

SECRET_KEY_BASE = "action_dispatch.secret_key_base"
SIGNED_COOKIE_DIGEST = "action_dispatch.signed_cookie_digest"
SIGNED_COOKIE_SALT = "action_dispatch.signed_cookie_salt"
USE_AUTHENTICATED_COOKIE_ENCRYPTION = "action_dispatch.use_authenticated_cookie_encryption"
USE_COOKIES_WITH_METADATA = "action_dispatch.use_cookies_with_metadata"

Class Public methods


# File actionpack/lib/action_dispatch/middleware/cookies.rb, line 683
def initialize(app)
  @app = app

Instance Public methods


# File actionpack/lib/action_dispatch/middleware/cookies.rb, line 687
def call(env)
  request =
  response =

  if request.have_cookie_jar?
    cookie_jar = request.cookie_jar
    unless cookie_jar.committed?
      response = Rack::Response[*response]