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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

Instance Attribute Summary

Instance Attribute Details

#cache_control (readonly)

[ GitHub ] 

  


# File 'actionpack/lib/action_dispatch/http/cache.rb', line 69



attr_reader :cache_control


  








  

    #date   (rw)
  

  [ 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)   (rw)
  

  [ GitHub ]


  

  


# File 'actionpack/lib/action_dispatch/http/cache.rb', line 95



def date=(utc_time)
  set_header DATE, utc_time.httpdate
end


  








  

    #date?  ⇒ Boolean  (rw)
  

  [ GitHub ]


  

  


# File 'actionpack/lib/action_dispatch/http/cache.rb', line 91



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.


  



  [ GitHub ]


  

  


# File 'actionpack/lib/action_dispatch/http/cache.rb', line 117



def etag=(weak_validators)
  self.weak_etag = weak_validators
end


  








  

    #etag?  ⇒ Boolean  (rw)
  

  [ GitHub ]


  

  


# File 'actionpack/lib/action_dispatch/http/cache.rb', line 129



def etag?; etag; end


  








  

    #last_modified   (rw)
  

  [ 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)   (rw)
  

  [ 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?  ⇒ Boolean  (rw)
  

  [ GitHub ]


  

  


# File 'actionpack/lib/action_dispatch/http/cache.rb', line 77



def last_modified?
  has_header? LAST_MODIFIED
end


  








  

    #strong_etag=(strong_validators)   (rw)
  

  [ 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?  ⇒ Boolean  (rw)
  



  

    

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


  





  


  [ GitHub ]


  

  


# File 'actionpack/lib/action_dispatch/http/cache.rb', line 138



def strong_etag?
  etag? && !weak_etag?
end


  








  

    #weak_etag=(weak_validators)   (rw)
  

  [ 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?  ⇒ Boolean  (rw)
  



  

    

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


  





  


  [ GitHub ]


  

  


# File 'actionpack/lib/action_dispatch/http/cache.rb', line 132



def weak_etag?
  etag? && etag.start_with?('W/"')
end