Class: Rack::ETag

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/etag.rb

Overview

Automatically sets the ETag header on all String bodies.

The ETag header is skipped if ETag or Last-Modified headers are sent or if a sendfile body (body.responds_to :to_path) is given (since such cases should be handled by apache/nginx).

On initialization, you can pass two parameters: a Cache-Control directive used when Etag is absent and a directive when it is present. The first defaults to nil, while the second defaults to “max-age=0, private, must-revalidate”

Constant Summary

DEFAULT_CACHE_CONTROL =
"max-age=0, private, must-revalidate".freeze

Instance Method Summary (collapse)

Constructor Details

- (ETag) initialize(app, no_cache_control = nil, cache_control = DEFAULT_CACHE_CONTROL)

Returns a new instance of ETag



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# File 'lib/rack/etag.rb', line 16

def initialize(app, no_cache_control = nil, cache_control = DEFAULT_CACHE_CONTROL)
  @app = app
  @cache_control = cache_control
  @no_cache_control = no_cache_control
end

Instance Method Details

- (Object) call(env)



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# File 'lib/rack/etag.rb', line 22

def call(env)
  status, headers, body = @app.call(env)

  if etag_status?(status) && etag_body?(body) && !skip_caching?(headers)
    original_body = body
    digest, new_body = digest_body(body)
    body = Rack::BodyProxy.new(new_body) do
      original_body.close if original_body.respond_to?(:close)
    end
    headers['ETag'] = %("#{digest}") if digest
  end

  unless headers['Cache-Control']
    if digest
      headers['Cache-Control'] = @cache_control if @cache_control
    else
      headers['Cache-Control'] = @no_cache_control if @no_cache_control
    end
  end

  [status, headers, body]
end