authorize.net error code 128 Using the ChildActionOnlyAttribute in Visual Studio .NET

Generator Code 128 in Visual Studio .NET Using the ChildActionOnlyAttribute

Listing 9.1 Using the ChildActionOnlyAttribute
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public class HomeController : Controller { public ActionResult Index() { return View(); } [ChildActionOnly] public ActionResult ChildAction() { return View(); } }
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Default Index action
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Action Filter applied to action
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The ChildActionOnly attribute prevents the ChildAction method from being exposed as a web-callable action that can be invoked by a web browser. But it can still be invoked by making a call to RenderAction from within a view, as follows:
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<%Html.RenderAction("ChildAction"); %>
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Accounting for filters in tests
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It may seem strange that the behavior defined in the attribute is called when the action is invoked. At runtime, the method isn t called directly; it s passed to the ControllerActionInvoker, which reads the action filters that are present on the controller and action. This is a nice extension point in the framework, because you re allowed to substitute your own IActionInvoker if you want to customize the semantics. During unit tests, you ll be calling action methods directly. None of the behavior defined in the action filters will be executed, so you should treat your tests as if the action filters were executed (for example, load any data into ViewData that would ve been loaded by an action filter). To test whether filters such as [Authorize] or [HttpPost] have been applied, you can easily test for the existence of the attribute by using reflection. Here s a class that can help you simplify the reflection code required to get attributes:
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public static class ReflectionExtensions { public static TAttribute GetAttribute<TAttribute>( this MemberInfo member) where TAttribute : Attribute {
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Action selectors
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(continued)
var attributes = member .GetCustomAttributes(typeof (TAttribute), true); if (attributes != null && attributes.Length > 0) return (TAttribute)attributes[0]; return null; } public static bool HasAttribute<TAttribute>( this MemberInfo member) where TAttribute : Attribute { return member.GetAttribute<TAttribute>() != null; } }
You can use this extension method as follows:
type.GetMethod("Index").HasAttribute<AcceptVerbsAttribute>()...
The extension method accepts the attribute type as a generic parameter and then ensures that the method in question is marked with that attribute.
Action selectors
The next extensibility point is the ActionMethodSelector. An action selector is different from an action filter, but the two are often confused because they re both applied to action methods by using attributes. The action selector is used to control which action method is selected to handle a particular route. There are a number of built-in action selectors, each used to filter down the actions so that you can have an action for a specific scenario. The list in figure 9.4 shows the action selectors that come with the framework. A common use for an action selector is to create an overloaded action to fulfill a route that differs only by the HTTP method that s sent to the web server. (Be aware that in this industry, the terms HTTP method and HTTP verb are used interchangeably.) A concrete example of this is to have two action methods named Edit . One would
Action selectors in ASP.NET MVC
Extending the controller
have the HttpGetAttribute applied and would render an edit form to the browser, and the other would have the HttpPostAttribute applied and would take a view model as a parameter. This simplifies the code in the view because the form from the first action is posted to the same URL. Essentially, the HTTP method is used to differentiate which overload should be invoked.
Using action results to reduce complexity
Custom action results can be used to remove code that s duplicated across methods and to extract dependencies that can make an action difficult to test. A great way to use a custom action result is to compose functionality on top of an out-of-the-box ActionResult, like the ViewResult or RedirectResult.
Removing duplication with an action result
To remove the duplication in multiple similar action methods, you can extract the majority of the code and move it into an action result. Listing 9.2 demonstrates how to take the logic for creating a comma-separated value (CSV) file from a collection of objects and encapsulate it within an action result.
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