Methods

Constants

DATE = "Date".freeze
DEFAULT_CACHE_CONTROL = "max-age=0, private, must-revalidate".freeze
LAST_MODIFIED = "Last-Modified".freeze
MUST_REVALIDATE = "must-revalidate".freeze
NO_CACHE = "no-cache".freeze
PRIVATE = "private".freeze
PUBLIC = "public".freeze
SPECIAL_KEYS = Set.new(%w[extras no-cache max-age public private must-revalidate])

Attributes

[R] cache_control

Instance Public methods

date()

📝 Source code 
# File actionpack/lib/action_dispatch/http/cache.rb, line 68
        def date
          if date_header = get_header(DATE)
            Time.httpdate(date_header)
          end
        end
🔎 See on GitHub

date=(utc_time)

📝 Source code 
# File actionpack/lib/action_dispatch/http/cache.rb, line 78
        def date=(utc_time)
          set_header DATE, utc_time.httpdate
        end
🔎 See on GitHub

date?()

📝 Source code 
# File actionpack/lib/action_dispatch/http/cache.rb, line 74
        def date?
          has_header? DATE
        end
🔎 See on GitHub

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 
# File actionpack/lib/action_dispatch/http/cache.rb, line 101
        def etag=(weak_validators)
          self.weak_etag = weak_validators
        end
🔎 See on GitHub

etag?()

📝 Source code 
# File actionpack/lib/action_dispatch/http/cache.rb, line 113
        def etag?; etag; end
🔎 See on GitHub

last_modified()

📝 Source code 
# File actionpack/lib/action_dispatch/http/cache.rb, line 54
        def last_modified
          if last = get_header(LAST_MODIFIED)
            Time.httpdate(last)
          end
        end
🔎 See on GitHub

last_modified=(utc_time)

📝 Source code 
# File actionpack/lib/action_dispatch/http/cache.rb, line 64
        def last_modified=(utc_time)
          set_header LAST_MODIFIED, utc_time.httpdate
        end
🔎 See on GitHub

last_modified?()

📝 Source code 
# File actionpack/lib/action_dispatch/http/cache.rb, line 60
        def last_modified?
          has_header? LAST_MODIFIED
        end
🔎 See on GitHub

strong_etag=(strong_validators)

📝 Source code 
# File actionpack/lib/action_dispatch/http/cache.rb, line 109
        def strong_etag=(strong_validators)
          set_header "ETag", generate_strong_etag(strong_validators)
        end
🔎 See on GitHub

strong_etag?()

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

📝 Source code 
# File actionpack/lib/action_dispatch/http/cache.rb, line 121
        def strong_etag?
          etag? && !weak_etag?
        end
🔎 See on GitHub

weak_etag=(weak_validators)

📝 Source code 
# File actionpack/lib/action_dispatch/http/cache.rb, line 105
        def weak_etag=(weak_validators)
          set_header "ETag", generate_weak_etag(weak_validators)
        end
🔎 See on GitHub

weak_etag?()

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

📝 Source code 
# File actionpack/lib/action_dispatch/http/cache.rb, line 116
        def weak_etag?
          etag? && etag.starts_with?('W/"')
        end
🔎 See on GitHub