MemoryTin

Unable to evaluate expression because the code is optimized or a nativeframe is on top of the call stack

When calling Response.Redirect from within a Try-Catch block you may get the error message ‘Unable to evaluate expression because the code is optimized or a native frame is on top of the call stack’. The exact reason for this is unknown to me but to fix the issue make sure that anytime Response.Rediredt is called int a Try-Catch you set the second parameter (EndResponse) to false so that the response if not killed after the return.

try
{
HttpContext.Current.Response.Redirect(
_targetUrl, false);
}
catch (Exception ex)
{
//Handle Exception
}

C# Inheritance Components

Class: Represent objects in code. Contain Fields (data storage), Methods (actions), Properties (attributes)

Interface: When an Interface is defined it lists out the public methods which must be created by any class which implements the Interface. It is a contract between objects stating that they will always provide their own implementations of a set of specific method signatures. This allows for other classes to accept an Interface type without knowing the details of its implementation, it only needs to know that the public contract methods are there for it to use.

Abstract Base Classes: When a class is declared as Abstract is prevents direct instantiation of the class in code. Instead a new class has to be created which derives from the Abstract class. This allows you to create a base class with base implementations but forces users of that class to derive their own classes from it in order to use the functionality.

Abstract Methods: When a base class declares a method as being Abstract it does not provide a default implementation and demands that all derived classes must override the method with its own implementation.

Virtual Methods: When a base class declares a method as being Virtual it provides a default implementation for that method but allows any derived classes to override the method with its own implementation.

C# This operation requires IIS integrated pipeline mode.

When trying to add Http Headers to your Response object you may get the error “This operation requires IIS integrated pipeline mode.” This is what looks like a bug in the .net framework. In order to work around this issue you should add the Http Headers to the Response using the following format.

HttpContext.Current.Response.AddHeader("ContentType", "application/x-www-form-urlencoded");

C# Custom Exceptions

[Serializable]
class AttributeNullException : Exception
{
/// 
/// Initializes a new instance of the  class.
/// 
/// The message.
public AttributeNullException(string message): base(message)
{
}
/// 
/// Initializes a new instance of the  class.
/// 
/// The message.
/// The inner exception.
public AttributeNullException(string message, Exception innerException): base(message, innerException)
{
}
/// 
/// Initializes a new instance of the  class.
/// 
/// The  that holds the serialized object data about the exception being thrown.
/// The  that contains contextual information about the source or destination.
/// 
/// The  parameter is null.
/// 
/// 
/// The class name is null or  is zero (0).
/// 
public AttributeNullException(SerializationInfo info, StreamingContext context): base(info, context)
{
}
}

JavaScript: Locate ASP.net Controls in HTML Markup

In ASP.net all controls are assigned a Unique Identifier (ID) so they can be referenced within your C# or VB code with ease. Most of use would, at least at first, assume we can use those very same ID’s in our JavaScript to manipulate those controls client side as well. Unfortunately not!

This is because ASP.net pages are made up of 10’s possibly 100’s of controls and any of those controls might be found embedded within other controls and its really hard to come up with unique ID’s for 100+ controls specially when you don’t the names used in 3rd party controls or the controls that come built into ASP.net. In order to handle these situations and in order to guarantee that each and every control has a unique ID within the HTML markup that gets generated .Net uses what are known as Naming Containers.

Naming Containers define a unique Namespace for all control ID’s within itself. There can be multiple Naming Containers on a page each with their own unique id, and each of these can then contain controls each with a unique id. But what is cool about it all is the unique ID’s can be reused across all the Naming Containers on a page. So a control named txtName can exist in more than one Naming container, but it has to remain unique within each of the containers.

Because of this Namespacing there becomes a need to guarantee that each control has a unique name in the rendered HTML. In order to accomplish this ASP.net pre-pends each unique control ID with each of its preceding Naming Containers up the chain. When you look for your control ID’s within the rendered markup you will see something like this ‘dnn_ctr8143_CrudImage_fuImage’.

This of course makes it very difficult to get a hold of your controls from within JavaScript. As long as your JavaScript is being rendered with the page by ASP.net there is a solution. You simply need to add a tag to your JavaScript on in your page or control markup which will give you the id of the control as it will appear within the final rendered markup. Or if you are adding scripts dynamically from within your C# or VB you can use a property of the control to get the id. The methods are as follows:

Within ASP.net Markup

Hide this content!
<div onclick="HideControl();return false;">

Dynamically C#

btnHide.OnClientClick("HideControl(" + pnlContent.ClientID + ");return false;");

HTML: Specifying a FavIcon Path

Place a link in your page head with the ‘rel’ attribute set to “SHORTCUT ICON” and the ‘href’ pointing to the location of your favicon. This way you don’t have to clutter up the root of your site with junk.