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module ActionController #:nodoc:
module Filters #:nodoc:
def self.included(base)
base.class_eval do
extend ClassMethods
include ActionController::Filters::InstanceMethods
end
end
class FilterChain < ActiveSupport::Callbacks::CallbackChain #:nodoc:
def append_filter_to_chain(filters, filter_type, &block)
pos = find_filter_append_position(filters, filter_type)
update_filter_chain(filters, filter_type, pos, &block)
end
def prepend_filter_to_chain(filters, filter_type, &block)
pos = find_filter_prepend_position(filters, filter_type)
update_filter_chain(filters, filter_type, pos, &block)
end
def create_filters(filters, filter_type, &block)
filters, conditions = extract_options(filters, &block)
filters.map! { |filter| find_or_create_filter(filter, filter_type, conditions) }
filters
end
def skip_filter_in_chain(*filters, &test)
filters, conditions = extract_options(filters)
filters.each do |filter|
if callback = find(filter) then delete(callback) end
end if conditions.empty?
update_filter_in_chain(filters, :skip => conditions, &test)
end
private
def update_filter_chain(filters, filter_type, pos, &block)
new_filters = create_filters(filters, filter_type, &block)
insert(pos, new_filters).flatten!
end
def find_filter_append_position(filters, filter_type)
# appending an after filter puts it at the end of the call chain
# before and around filters go before the first after filter in the chain
unless filter_type == :after
each_with_index do |f,i|
return i if f.after?
end
end
return -1
end
def find_filter_prepend_position(filters, filter_type)
# prepending a before or around filter puts it at the front of the call chain
# after filters go before the first after filter in the chain
if filter_type == :after
each_with_index do |f,i|
return i if f.after?
end
return -1
end
return 0
end
def find_or_create_filter(filter, filter_type, options = {})
update_filter_in_chain([filter], options)
if found_filter = find(filter) { |f| f.type == filter_type }
found_filter
else
filter_kind = case
when filter.respond_to?(:before) && filter_type == :before
:before
when filter.respond_to?(:after) && filter_type == :after
:after
else
:filter
end
case filter_type
when :before
BeforeFilter.new(filter_kind, filter, options)
when :after
AfterFilter.new(filter_kind, filter, options)
else
AroundFilter.new(filter_kind, filter, options)
end
end
end
def update_filter_in_chain(filters, options, &test)
filters.map! { |f| block_given? ? find(f, &test) : find(f) }
filters.compact!
map! do |filter|
if filters.include?(filter)
new_filter = filter.dup
new_filter.update_options!(options)
new_filter
else
filter
end
end
end
end
class Filter < ActiveSupport::Callbacks::Callback #:nodoc:
def initialize(kind, method, options = {})
super
update_options! options
end
# override these to return true in appropriate subclass
def before?
false
end
def after?
false
end
def around?
false
end
# Make sets of strings from :only/:except options
def update_options!(other)
if other
convert_only_and_except_options_to_sets_of_strings(other)
if other[:skip]
convert_only_and_except_options_to_sets_of_strings(other[:skip])
end
end
options.update(other)
end
private
def should_not_skip?(controller)
if options[:skip]
!included_in_action?(controller, options[:skip])
else
true
end
end
def included_in_action?(controller, options)
if options[:only]
options[:only].include?(controller.action_name)
elsif options[:except]
!options[:except].include?(controller.action_name)
else
true
end
end
def should_run_callback?(controller)
should_not_skip?(controller) && included_in_action?(controller, options) && super
end
def convert_only_and_except_options_to_sets_of_strings(opts)
[:only, :except].each do |key|
if values = opts[key]
opts[key] = Array(values).map(&:to_s).to_set
end
end
end
end
class AroundFilter < Filter #:nodoc:
def type
:around
end
def around?
true
end
def call(controller, &block)
if should_run_callback?(controller)
method = filter_responds_to_before_and_after? ? around_proc : self.method
# For around_filter do |controller, action|
if method.is_a?(Proc) && method.arity == 2
evaluate_method(method, controller, block)
else
evaluate_method(method, controller, &block)
end
else
block.call
end
end
private
def filter_responds_to_before_and_after?
method.respond_to?(:before) && method.respond_to?(:after)
end
def around_proc
Proc.new do |controller, action|
method.before(controller)
if controller.__send__(:performed?)
controller.__send__(:halt_filter_chain, method, :rendered_or_redirected)
else
begin
action.call
ensure
method.after(controller)
end
end
end
end
end
class BeforeFilter < Filter #:nodoc:
def type
:before
end
def before?
true
end
def call(controller, &block)
super
if controller.__send__(:performed?)
controller.__send__(:halt_filter_chain, method, :rendered_or_redirected)
end
end
end
class AfterFilter < Filter #:nodoc:
def type
:after
end
def after?
true
end
end
# Filters enable controllers to run shared pre- and post-processing code for its actions. These filters can be used to do
# authentication, caching, or auditing before the intended action is performed. Or to do localization or output
# compression after the action has been performed. Filters have access to the request, response, and all the instance
# variables set by other filters in the chain or by the action (in the case of after filters).
#
# == Filter inheritance
#
# Controller inheritance hierarchies share filters downwards, but subclasses can also add or skip filters without
# affecting the superclass. For example:
#
# class BankController < ActionController::Base
# before_filter :audit
#
# private
# def audit
# # record the action and parameters in an audit log
# end
# end
#
# class VaultController < BankController
# before_filter :verify_credentials
#
# private
# def verify_credentials
# # make sure the user is allowed into the vault
# end
# end
#
# Now any actions performed on the BankController will have the audit method called before. On the VaultController,
# first the audit method is called, then the verify_credentials method. If the audit method renders or redirects, then
# verify_credentials and the intended action are never called.
#
# == Filter types
#
# A filter can take one of three forms: method reference (symbol), external class, or inline method (proc). The first
# is the most common and works by referencing a protected or private method somewhere in the inheritance hierarchy of
# the controller by use of a symbol. In the bank example above, both BankController and VaultController use this form.
#
# Using an external class makes for more easily reused generic filters, such as output compression. External filter classes
# are implemented by having a static +filter+ method on any class and then passing this class to the filter method. Example:
#
# class OutputCompressionFilter
# def self.filter(controller)
# controller.response.body = compress(controller.response.body)
# end
# end
#
# class NewspaperController < ActionController::Base
# after_filter OutputCompressionFilter
# end
#
# The filter method is passed the controller instance and is hence granted access to all aspects of the controller and can
# manipulate them as it sees fit.
#
# The inline method (using a proc) can be used to quickly do something small that doesn't require a lot of explanation.
# Or just as a quick test. It works like this:
#
# class WeblogController < ActionController::Base
# before_filter { |controller| head(400) if controller.params["stop_action"] }
# end
#
# As you can see, the block expects to be passed the controller after it has assigned the request to the internal variables.
# This means that the block has access to both the request and response objects complete with convenience methods for params,
# session, template, and assigns. Note: The inline method doesn't strictly have to be a block; any object that responds to call
# and returns 1 or -1 on arity will do (such as a Proc or an Method object).
#
# Please note that around_filters function a little differently than the normal before and after filters with regard to filter
# types. Please see the section dedicated to around_filters below.
#
# == Filter chain ordering
#
# Using <tt>before_filter</tt> and <tt>after_filter</tt> appends the specified filters to the existing chain. That's usually
# just fine, but some times you care more about the order in which the filters are executed. When that's the case, you
# can use <tt>prepend_before_filter</tt> and <tt>prepend_after_filter</tt>. Filters added by these methods will be put at the
# beginning of their respective chain and executed before the rest. For example:
#
# class ShoppingController < ActionController::Base
# before_filter :verify_open_shop
#
# class CheckoutController < ShoppingController
# prepend_before_filter :ensure_items_in_cart, :ensure_items_in_stock
#
# The filter chain for the CheckoutController is now <tt>:ensure_items_in_cart, :ensure_items_in_stock,</tt>
# <tt>:verify_open_shop</tt>. So if either of the ensure filters renders or redirects, we'll never get around to see if the shop
# is open or not.
#
# You may pass multiple filter arguments of each type as well as a filter block.
# If a block is given, it is treated as the last argument.
#
# == Around filters
#
# Around filters wrap an action, executing code both before and after.
# They may be declared as method references, blocks, or objects responding
# to +filter+ or to both +before+ and +after+.
#
# To use a method as an +around_filter+, pass a symbol naming the Ruby method.
# Yield (or <tt>block.call</tt>) within the method to run the action.
#
# around_filter :catch_exceptions
#
# private
# def catch_exceptions
# yield
# rescue => exception
# logger.debug "Caught exception! #{exception}"
# raise
# end
#
# To use a block as an +around_filter+, pass a block taking as args both
# the controller and the action block. You can't call yield directly from
# an +around_filter+ block; explicitly call the action block instead:
#
# around_filter do |controller, action|
# logger.debug "before #{controller.action_name}"
# action.call
# logger.debug "after #{controller.action_name}"
# end
#
# To use a filter object with +around_filter+, pass an object responding
# to <tt>:filter</tt> or both <tt>:before</tt> and <tt>:after</tt>. With a
# filter method, yield to the block as above:
#
# around_filter BenchmarkingFilter
#
# class BenchmarkingFilter
# def self.filter(controller, &block)
# Benchmark.measure(&block)
# end
# end
#
# With +before+ and +after+ methods:
#
# around_filter Authorizer.new
#
# class Authorizer
# # This will run before the action. Redirecting aborts the action.
# def before(controller)
# unless user.authorized?
# redirect_to(login_url)
# end
# end
#
# # This will run after the action if and only if before did not render or redirect.
# def after(controller)
# end
# end
#
# If the filter has +before+ and +after+ methods, the +before+ method will be
# called before the action. If +before+ renders or redirects, the filter chain is
# halted and +after+ will not be run. See Filter Chain Halting below for
# an example.
#
# == Filter chain skipping
#
# Declaring a filter on a base class conveniently applies to its subclasses,
# but sometimes a subclass should skip some of its superclass' filters:
#
# class ApplicationController < ActionController::Base
# before_filter :authenticate
# around_filter :catch_exceptions
# end
#
# class WeblogController < ApplicationController
# # Will run the :authenticate and :catch_exceptions filters.
# end
#
# class SignupController < ApplicationController
# # Skip :authenticate, run :catch_exceptions.
# skip_before_filter :authenticate
# end
#
# class ProjectsController < ApplicationController
# # Skip :catch_exceptions, run :authenticate.
# skip_filter :catch_exceptions
# end
#
# class ClientsController < ApplicationController
# # Skip :catch_exceptions and :authenticate unless action is index.
# skip_filter :catch_exceptions, :authenticate, :except => :index
# end
#
# == Filter conditions
#
# Filters may be limited to specific actions by declaring the actions to
# include or exclude. Both options accept single actions
# (<tt>:only => :index</tt>) or arrays of actions
# (<tt>:except => [:foo, :bar]</tt>).
#
# class Journal < ActionController::Base
# # Require authentication for edit and delete.
# before_filter :authorize, :only => [:edit, :delete]
#
# # Passing options to a filter with a block.
# around_filter(:except => :index) do |controller, action_block|
# results = Profiler.run(&action_block)
# controller.response.sub! "</body>", "#{results}</body>"
# end
#
# private
# def authorize
# # Redirect to login unless authenticated.
# end
# end
#
# == Filter Chain Halting
#
# <tt>before_filter</tt> and <tt>around_filter</tt> may halt the request
# before a controller action is run. This is useful, for example, to deny
# access to unauthenticated users or to redirect from HTTP to HTTPS.
# Simply call render or redirect. After filters will not be executed if the filter
# chain is halted.
#
# Around filters halt the request unless the action block is called.
# Given these filters
# after_filter :after
# around_filter :around
# before_filter :before
#
# The filter chain will look like:
#
# ...
# . \
# . #around (code before yield)
# . . \
# . . #before (actual filter code is run)
# . . . \
# . . . execute controller action
# . . . /
# . . ...
# . . /
# . #around (code after yield)
# . /
# #after (actual filter code is run, unless the around filter does not yield)
#
# If +around+ returns before yielding, +after+ will still not be run. The +before+
# filter and controller action will not be run. If +before+ renders or redirects,
# the second half of +around+ and will still run but +after+ and the
# action will not. If +around+ fails to yield, +after+ will not be run.
module ClassMethods
# The passed <tt>filters</tt> will be appended to the filter_chain and
# will execute before the action on this controller is performed.
def append_before_filter(*filters, &block)
filter_chain.append_filter_to_chain(filters, :before, &block)
end
# The passed <tt>filters</tt> will be prepended to the filter_chain and
# will execute before the action on this controller is performed.
def prepend_before_filter(*filters, &block)
filter_chain.prepend_filter_to_chain(filters, :before, &block)
end
# Shorthand for append_before_filter since it's the most common.
alias :before_filter :append_before_filter
# The passed <tt>filters</tt> will be appended to the array of filters
# that run _after_ actions on this controller are performed.
def append_after_filter(*filters, &block)
filter_chain.append_filter_to_chain(filters, :after, &block)
end
# The passed <tt>filters</tt> will be prepended to the array of filters
# that run _after_ actions on this controller are performed.
def prepend_after_filter(*filters, &block)
filter_chain.prepend_filter_to_chain(filters, :after, &block)
end
# Shorthand for append_after_filter since it's the most common.
alias :after_filter :append_after_filter
# If you <tt>append_around_filter A.new, B.new</tt>, the filter chain looks like
#
# B#before
# A#before
# # run the action
# A#after
# B#after
#
# With around filters which yield to the action block, +before+ and +after+
# are the code before and after the yield.
def append_around_filter(*filters, &block)
filter_chain.append_filter_to_chain(filters, :around, &block)
end
# If you <tt>prepend_around_filter A.new, B.new</tt>, the filter chain looks like:
#
# A#before
# B#before
# # run the action
# B#after
# A#after
#
# With around filters which yield to the action block, +before+ and +after+
# are the code before and after the yield.
def prepend_around_filter(*filters, &block)
filter_chain.prepend_filter_to_chain(filters, :around, &block)
end
# Shorthand for +append_around_filter+ since it's the most common.
alias :around_filter :append_around_filter
# Removes the specified filters from the +before+ filter chain. Note that this only works for skipping method-reference
# filters, not procs. This is especially useful for managing the chain in inheritance hierarchies where only one out
# of many sub-controllers need a different hierarchy.
#
# You can control the actions to skip the filter for with the <tt>:only</tt> and <tt>:except</tt> options,
# just like when you apply the filters.
def skip_before_filter(*filters)
filter_chain.skip_filter_in_chain(*filters, &:before?)
end
# Removes the specified filters from the +after+ filter chain. Note that this only works for skipping method-reference
# filters, not procs. This is especially useful for managing the chain in inheritance hierarchies where only one out
# of many sub-controllers need a different hierarchy.
#
# You can control the actions to skip the filter for with the <tt>:only</tt> and <tt>:except</tt> options,
# just like when you apply the filters.
def skip_after_filter(*filters)
filter_chain.skip_filter_in_chain(*filters, &:after?)
end
# Removes the specified filters from the filter chain. This only works for method reference (symbol)
# filters, not procs. This method is different from skip_after_filter and skip_before_filter in that
# it will match any before, after or yielding around filter.
#
# You can control the actions to skip the filter for with the <tt>:only</tt> and <tt>:except</tt> options,
# just like when you apply the filters.
def skip_filter(*filters)
filter_chain.skip_filter_in_chain(*filters)
end
# Returns an array of Filter objects for this controller.
def filter_chain
if chain = read_inheritable_attribute('filter_chain')
return chain
else
write_inheritable_attribute('filter_chain', FilterChain.new)
return filter_chain
end
end
# Returns all the before filters for this class and all its ancestors.
# This method returns the actual filter that was assigned in the controller to maintain existing functionality.
def before_filters #:nodoc:
filter_chain.select(&:before?).map(&:method)
end
# Returns all the after filters for this class and all its ancestors.
# This method returns the actual filter that was assigned in the controller to maintain existing functionality.
def after_filters #:nodoc:
filter_chain.select(&:after?).map(&:method)
end
end
module InstanceMethods # :nodoc:
def self.included(base)
base.class_eval do
alias_method_chain :perform_action, :filters
alias_method_chain :process, :filters
end
end
protected
def process_with_filters(request, response, method = :perform_action, *arguments) #:nodoc:
@before_filter_chain_aborted = false
process_without_filters(request, response, method, *arguments)
end
def perform_action_with_filters
call_filters(self.class.filter_chain, 0, 0)
end
private
def call_filters(chain, index, nesting)
index = run_before_filters(chain, index, nesting)
aborted = @before_filter_chain_aborted
perform_action_without_filters unless performed? || aborted
return index if nesting != 0 || aborted
run_after_filters(chain, index)
end
def run_before_filters(chain, index, nesting)
while chain[index]
filter, index = chain[index], index
break unless filter # end of call chain reached
case filter
when BeforeFilter
filter.call(self) # invoke before filter
index = index.next
break if @before_filter_chain_aborted
when AroundFilter
yielded = false
filter.call(self) do
yielded = true
# all remaining before and around filters will be run in this call
index = call_filters(chain, index.next, nesting.next)
end
halt_filter_chain(filter, :did_not_yield) unless yielded
break
else
break # no before or around filters left
end
end
index
end
def run_after_filters(chain, index)
seen_after_filter = false
while chain[index]
filter, index = chain[index], index
break unless filter # end of call chain reached
case filter
when AfterFilter
seen_after_filter = true
filter.call(self) # invoke after filter
else
# implementation error or someone has mucked with the filter chain
raise ActionControllerError, "filter #{filter.inspect} was in the wrong place!" if seen_after_filter
end
index = index.next
end
index.next
end
def halt_filter_chain(filter, reason)
@before_filter_chain_aborted = true
logger.info "Filter chain halted as [#{filter.inspect}] #{reason}." if logger
end
end
end
end
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