Module: ActionDispatch::Http::Cache::Response
- Included in:
- Response
- Defined in:
- actionpack/lib/action_dispatch/http/cache.rb
Instance Attribute Summary collapse
-
#cache_control ⇒ Object
readonly
Returns the value of attribute cache_control.
Instance Method Summary collapse
- #date ⇒ Object
- #date=(utc_time) ⇒ Object
- #date? ⇒ Boolean
-
#etag=(weak_validators) ⇒ Object
This method sets a weak ETag validator on the response so browsers and proxies may cache the response, keyed on the ETag.
- #etag? ⇒ Boolean
- #last_modified ⇒ Object
- #last_modified=(utc_time) ⇒ Object
- #last_modified? ⇒ Boolean
- #strong_etag=(strong_validators) ⇒ Object
-
#strong_etag? ⇒ Boolean
True if an ETag is set, and it isn’t a weak validator (not preceded with ‘W/`).
- #weak_etag=(weak_validators) ⇒ Object
-
#weak_etag? ⇒ Boolean
True if an ETag is set, and it’s a weak validator (preceded with ‘W/`).
Instance Attribute Details
#cache_control ⇒ Object (readonly)
Returns the value of attribute cache_control.
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 177 def cache_control @cache_control end |
Instance Method Details
#date ⇒ Object
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 193 def date if date_header = get_header(DATE) Time.httpdate(date_header) end end |
#date=(utc_time) ⇒ Object
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 203 def date=(utc_time) set_header DATE, utc_time.httpdate end |
#date? ⇒ Boolean
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 199 def date? has_header? DATE end |
#etag=(weak_validators) ⇒ Object
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.
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 225 def etag=(weak_validators) self.weak_etag = weak_validators end |
#etag? ⇒ Boolean
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 237 def etag?; etag; end |
#last_modified ⇒ Object
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 179 def last_modified if last = get_header(LAST_MODIFIED) Time.httpdate(last) end end |
#last_modified=(utc_time) ⇒ Object
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 189 def last_modified=(utc_time) set_header LAST_MODIFIED, utc_time.httpdate end |
#last_modified? ⇒ Boolean
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 185 def last_modified? has_header? LAST_MODIFIED end |
#strong_etag=(strong_validators) ⇒ Object
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 233 def strong_etag=(strong_validators) set_header "ETag", generate_strong_etag(strong_validators) end |
#strong_etag? ⇒ Boolean
True if an ETag is set, and it isn’t a weak validator (not preceded with ‘W/`).
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 246 def strong_etag? etag? && !weak_etag? end |
#weak_etag=(weak_validators) ⇒ Object
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 229 def weak_etag=(weak_validators) set_header "ETag", generate_weak_etag(weak_validators) end |
#weak_etag? ⇒ Boolean
True if an ETag is set, and it’s a weak validator (preceded with ‘W/`).
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# File 'actionpack/lib/action_dispatch/http/cache.rb', line 240 def weak_etag? etag? && etag.start_with?('W/"') end |