class Rack::ETag

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”

Constants

DEFAULT_CACHE_CONTROL
ETAG_STRING

Public Class Methods

new (app, no_cache_control = nil, cache_control = DEFAULT_CACHE_CONTROL)

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

Public Instance Methods

call (env)

# File lib/rack/etag.rb, line 28
def call(env)
  status, headers, body = response = @app.call(env)

  if etag_status?(status) && body.respond_to?(:to_ary) && !skip_caching?(headers)
    body = body.to_ary
    digest = digest_body(body)
    headers[ETAG_STRING] = %(W/"#{digest}") if digest

    # Body was modified, so we need to re-assign it:
    response[2] = body
  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

  response
end