Filter Chain Ordering in Java

Creator QR-Code in Java Filter Chain Ordering
473 Filter Chain Ordering
QR Code 2d Barcode Drawer In Java
Using Barcode encoder for Java Control to generate, create Denso QR Bar Code image in Java applications.
Using before_filter and after_filter appends the specified filters to the existing chain That s usually just fine, but sometimes you care more about the order in which the filters are executed When that s the case, you can use prepend_before_filter and prepend_after_filter Filters added by these methods will be put at the beginning of their respective chain and executed before the rest, like the example in Listing 43
Bar Code Encoder In Java
Using Barcode creator for Java Control to generate, create bar code image in Java applications.
Listing 43 An example of prepending before filters class ShoppingController < ActionController::Base before_filter :verify_open_shop class CheckoutController < ShoppingController prepend_before_filter :ensure_items_in_cart, :ensure_items_in_stock
Decode Barcode In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
The filter chain for the CheckoutController is now :ensure_items_in_cart,
Paint QR Code In C#.NET
Using Barcode encoder for VS .NET Control to generate, create QR Code image in VS .NET applications.
:ensure_items_in_stock, :verify_open_shop So if either of the ensure filters
Make Quick Response Code In .NET Framework
Using Barcode encoder for ASP.NET Control to generate, create QR image in ASP.NET applications.
halts execution, we ll never get around to seeing if the shop is open
QR Code JIS X 0510 Generation In .NET Framework
Using Barcode drawer for VS .NET Control to generate, create Quick Response Code image in Visual Studio .NET applications.
47 Filters
Make QR Code ISO/IEC18004 In VB.NET
Using Barcode printer for Visual Studio .NET Control to generate, create QR Code 2d barcode image in Visual Studio .NET applications.
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
EAN13 Generation In Java
Using Barcode creation for Java Control to generate, create EAN 13 image in Java applications.
474 Around Filters
UCC.EAN - 128 Creation In Java
Using Barcode printer for Java Control to generate, create UCC-128 image in Java applications.
Around filters wrap an action, executing code both before and after the action that they wrap They may be declared as method references, blocks, or objects with an around class method To use a method as an around_filter, pass a symbol naming the Ruby method Use yield within the method to run the action For example, Listing 44 has an around filter that logs exceptions (not that you need to do anything like this in your application; it s just an example)
Print ANSI/AIM Code 39 In Java
Using Barcode generation for Java Control to generate, create Code39 image in Java applications.
Listing 44 An around filter to log exceptions around_filter :catch_exceptions private def catch_exceptions yield rescue => exception loggerdebug "Caught exception! #{exception}" raise end
Barcode Creation In Java
Using Barcode creation for Java Control to generate, create barcode image in Java applications.
Controllers
Create Barcode In Java
Using Barcode printer for Java Control to generate, create bar code image in Java applications.
To use a block as an around_filter, pass a block taking as args both the controller and the action parameters You can t call yield from blocks in Ruby, so explicitly invoke call on the action parameter:
4-State Customer Barcode Drawer In Java
Using Barcode drawer for Java Control to generate, create Intelligent Mail image in Java applications.
around_filter do |controller, action| loggerdebug "before #{controlleraction_name}" actioncall loggerdebug "after #{controlleraction_name}" end
Code 39 Full ASCII Reader In .NET Framework
Using Barcode reader for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.
Tim says
Painting GS1 128 In Visual Studio .NET
Using Barcode drawer for ASP.NET Control to generate, create UCC - 12 image in ASP.NET applications.
Since processing of filter blocks is done with instance_eval, you don t actually have to use the controller parameter in Rails 3 It s there for backward-compatibility reasons
Code 39 Creation In C#
Using Barcode creation for VS .NET Control to generate, create Code 3 of 9 image in .NET applications.
4: Working with Controllers
Barcode Scanner In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
To use a filter object with around_filter, pass an object responding to :around With a filter method, yield to the block like this:
GS1 - 12 Reader In VS .NET
Using Barcode reader for .NET framework Control to read, scan read, scan image in .NET applications.
around_filter BenchmarkingFilter class BenchmarkingFilter def selfaround(controller) Benchmarkmeasure { yield } end end
Draw EAN13 In .NET Framework
Using Barcode printer for ASP.NET Control to generate, create UPC - 13 image in ASP.NET applications.
475 Filter Chain Skipping
Make Code 128A In .NET Framework
Using Barcode generation for ASP.NET Control to generate, create Code 128 Code Set A image in ASP.NET applications.
Declaring a filter on a base class conveniently applies to its subclasses, but sometimes a subclass should skip some of the filters it inherits from a superclass:
class ApplicationController < ActionController::Base before_filter :authenticate around_filter :catch_exceptions end class SignupController < ApplicationController skip_before_filter :authenticate end class HackedTogetherController < ApplicationController skip_filter :catch_exceptions end
476 Filter Conditions
Filters may be limited to specific actions by declaring the actions to include or exclude, using :only or :except options Both options accept single actions (like :only => :index) or arrays of actions (:except => [:foo, :bar])
class Journal < ActionController::Base before_filter :authorize, :only => [:edit, :delete] around_filter :except => :index do |controller, action_block| results = Profilerrun(&action_block) controllerresponsesub! "</body>", "#{results}</body>" end private def authorize # Redirect to login unless authenticated end end
48 Verification
477 Filter Chain Halting
The before_filter and around_filter methods may halt the request before the body of a controller action method is run This is useful, for example, to deny access to unauthenticated users As mentioned earlier, all you have to do to halt the before filter chain is call render or redirect_to After filters will not be executed if the before filter chain is halted Around filters halt the request unless the action block is called If an around filter returns before yielding, it is effectively halting the chain and any after filters will not be run
Controllers
48 Veri cation
This official Rails verification plugin5 provides a class-level method for specifying that certain actions are guarded against being called without certain prerequisites being met It is essentially a special kind of before_filter An action may be guarded against being invoked without certain request parameters being set or without certain session values existing When a verification is violated, values may be inserted into the flash and a redirection triggered If no specific action is configured, verification failure will in a 400 Bad Request response Note that these verifications are apart from the business rules expressed in your models They do not examine the content of the session or the parameters nor do they replace model validations