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Constants
DATE | = | "Date" |
DEFAULT_CACHE_CONTROL | = | "max-age=0, private, must-revalidate" |
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 |
Instance Public methods
date() Link
date=(utc_time) Link
date?() Link
etag=(weak_validators) Link
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.
etag?() Link
last_modified() Link
last_modified=(utc_time) Link
last_modified?() Link
strong_etag=(strong_validators) Link
strong_etag?() Link
True if an ETag is set, and it isn’t a weak validator (not preceded with W/
).