Module: ActionDispatch::Http::Cache::Response
Relationships & Source Files | |
Extension / Inclusion / Inheritance Descendants | |
Included In:
ActionController::Live::Response,
::ActionController::LiveTestResponse ,
::ActionDispatch::Response ,
::ActionDispatch::TestResponse
| |
Defined in: | actionpack/lib/action_dispatch/http/cache.rb |
Constant Summary
-
DATE =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 126"Date"
-
DEFAULT_CACHE_CONTROL =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 166"max-age=0, private, must-revalidate"
-
LAST_MODIFIED =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 127"Last-Modified"
-
MUST_REVALIDATE =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 171"must-revalidate"
-
NO_CACHE =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 168"no-cache"
-
NO_STORE =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 167"no-store"
-
PRIVATE =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 170"private"
-
PUBLIC =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 169"public"
-
SPECIAL_KEYS =
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 128Set.new(%w[extras no-store no-cache max-age public private must-revalidate])
Instance Attribute Summary
- #cache_control readonly
- #date rw
- #date=(utc_time) rw
- #date? ⇒ Boolean rw
-
#etag=(weak_validators)
rw
This method sets a weak ETag validator on the response so browsers and proxies may cache the response, keyed on the ETag.
- #etag? ⇒ Boolean rw
- #last_modified rw
- #last_modified=(utc_time) rw
- #last_modified? ⇒ Boolean rw
- #strong_etag=(strong_validators) rw
-
#strong_etag? ⇒ Boolean
rw
True if an ETag is set, and it isn’t a weak validator (not preceded with
W/
). - #weak_etag=(weak_validators) rw
-
#weak_etag? ⇒ Boolean
rw
True if an ETag is set, and it’s a weak validator (preceded with
W/
).
Instance Attribute Details
#cache_control (readonly)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 52
attr_reader :cache_control
#date (rw)
[ GitHub ]#date=(utc_time) (rw)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 78
def date=(utc_time) set_header DATE, utc_time.httpdate end
#date? ⇒ Boolean
(rw)
[ GitHub ]
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 74
def date? has_header? DATE end
#etag=(weak_validators) (rw)
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.
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 101
def etag=(weak_validators) self.weak_etag = weak_validators end
#etag? ⇒ Boolean
(rw)
[ GitHub ]
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 113
def etag?; etag; end
#last_modified (rw)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 54
def last_modified if last = get_header(LAST_MODIFIED) Time.httpdate(last) end end
#last_modified=(utc_time) (rw)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 64
def last_modified=(utc_time) set_header LAST_MODIFIED, utc_time.httpdate end
#last_modified? ⇒ Boolean
(rw)
[ GitHub ]
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 60
def last_modified? has_header? LAST_MODIFIED end
#strong_etag=(strong_validators) (rw)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 109
def strong_etag=(strong_validators) set_header "ETag", generate_strong_etag(strong_validators) end
#strong_etag? ⇒ Boolean
(rw)
True if an ETag is set, and it isn’t a weak validator (not preceded with W/
).
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 121
def strong_etag? etag? && !weak_etag? end
#weak_etag=(weak_validators) (rw)
[ GitHub ]# File 'actionpack/lib/action_dispatch/http/cache.rb', line 105
def weak_etag=(weak_validators) set_header "ETag", generate_weak_etag(weak_validators) end
#weak_etag? ⇒ Boolean
(rw)
True if an ETag is set, and it’s a weak validator (preceded with W/
).
# File 'actionpack/lib/action_dispatch/http/cache.rb', line 116
def weak_etag? etag? && etag.start_with?('W/"') end