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module ActionDispatch::Http::Cache::Response

Constants

DATE

"Date"

DEFAULT_CACHE_CONTROL

"max-age=0, private, must-revalidate"

IMMUTABLE

"immutable"

LAST_MODIFIED

"Last-Modified"

MUST_REVALIDATE

"must-revalidate"

NO_CACHE

"no-cache"

NO_STORE

"no-store"

PRIVATE

"private"

PUBLIC

"public"

SPECIAL_KEYS

Set.new(%w[extras no-store no-cache max-age public private must-revalidate])

Attributes

[R] cache_control

Public instance methods

date()

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 85
def date
  if date_header = get_header(DATE)
    Time.httpdate(date_header)
  end
end

date=(utc_time)

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 95
def date=(utc_time)
  set_header DATE, utc_time.httpdate
end

date?()

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 91
def date?
  has_header? DATE
end

etag=(weak_validators)

This method sets a weak ETag validator on the response so browsers and proxies may cache the response, keyed on the ETag. On subsequent requests, the If-None-Match header is set to the cached ETag. If it matches the current ETag, we can return a 304 Not Modified response with no body, letting the browser or proxy know that their cache is current. Big savings in request time and network bandwidth.

Weak ETags are considered to be semantically equivalent but not byte-for-byte identical. This is perfect for browser caching of HTML pages where we don’t care about exact equality, just what the user is viewing.

Strong ETags are considered byte-for-byte identical. They allow a browser or proxy cache to support Range requests, useful for paging through a PDF file or scrubbing through a video. Some CDNs only support strong ETags and will ignore weak ETags entirely.

Weak ETags are what we almost always need, so they’re the default. Check out

strong_etag= to provide a strong ETag validator.

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 117
def etag=(weak_validators)
  self.weak_etag = weak_validators
end

etag?()

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 129
def etag?; etag; end

last_modified()

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 71
def last_modified
  if last = get_header(LAST_MODIFIED)
    Time.httpdate(last)
  end
end

last_modified=(utc_time)

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 81
def last_modified=(utc_time)
  set_header LAST_MODIFIED, utc_time.httpdate
end

last_modified?()

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 77
def last_modified?
  has_header? LAST_MODIFIED
end

strong_etag=(strong_validators)

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 125
def strong_etag=(strong_validators)
  set_header "ETag", generate_strong_etag(strong_validators)
end

strong_etag?()

True if an ETag is set, and it isn’t a weak validator (not preceded with W/).

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 138
def strong_etag?
  etag? && !weak_etag?
end

weak_etag=(weak_validators)

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 121
def weak_etag=(weak_validators)
  set_header "ETag", generate_weak_etag(weak_validators)
end

weak_etag?()

True if an ETag is set, and it’s a weak validator (preceded with W/).

Source code GitHub 
# File actionpack/lib/action_dispatch/http/cache.rb, line 132
def weak_etag?
  etag? && etag.start_with?('W/"')
end

Definition files