Beginning Ajax With ASP.NET (2006).pdf

Chapter 9
this.txtTitle.Attributes.Add(“onmouseout”,
“ChangeCSSClass(this,’mouseOut’);”);
}
if (this.Session[“title”] != null)
{
this.txtTitle.Text = this.Session[“title”].ToString();
}
}
}
protected void txtTitle_TextChanged(object sender, EventArgs e)
{
this.Session.Add(“title”,this.txtTitle.Text);
this.txtTitle.AutoUpdateAfterCallBack = true;
}
Although much of this implementation is similar to the MagicAjax demonstration, notice the different
approaches. Using Anthem.NET you declare an Anthem TextBox control and use the built-in mechanism
of firing the TextChanged event to initiate a request to the server. Once the server is contacted, you
can apply the Session value and set the AutoUpdateAfterCallBack property on the TextBox control
equal to true.
You can now test the behavior by launching the page in the browser.
Example 7: Server Exceptions
A feature exclusive to Anthem.NET from all the frameworks listed in this section is the ability to deal
with unhandled server-side exceptions. In other frameworks, should your application encounter an
unhandled exception, the error may bubble up to the user interface as the cryptic and intimidating stock
yellow and white ASP.NET error page. While the subject of structured exception management is out of
the scope of this book, you will implement an example that will enforce this foundational rule: protect
the user from useless error messages.
Anthem.NET will wrap up unhandled exceptions into a JSON error object. When you encounter this
object, you may then decide what to do on the client with the error. The response object returned by
Anthem.NET includes an error object in its interface. If the error property is not null, then you have
encountered an error on the server.
Figure 9-17 shows an example of how the page will appear when Anthem wraps up an unhandled
server exception.
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