ASP.net

Nested Master Page Events not being called

9/10/2008

Nested Master Page Events not being called This is the second time I've been caught out by this little feature, so I thought I'd geekzilla it for both reference and to help others. Scenario I'm a big fan of MasterPages and Themes as a design principle for web development, and often you need to nest master pages to create complex repeatable layouts. The Feature In my child MasterPage I decided to put some code in the Page_Load to populate a related menu, and it wasn't being called....... very strange.. The Top level MasterPages' events were being called, but the child's weren't! Solution I'm not sure why it defaults to false but.. you need to change the AutoEventWireup property to '''true''' in the Master Directive in the MasterPage. If this has caught you out, here's the solution.

Displaying XML just like Internet Explorer

4/1/2008

Displaying XML just like Internet Explorer This is everything you need to display XML in your webpage the same way IE displays it when you open an XML document in IE. Html Register the js and place a literal where you'd like the XML to appear. Code Behind Some dummy XML for this example The following applies an XSLt to your xml XSLt The XSLt required for the transformation CSS JS The JavaScript required to expand and collapse the XML document nodes.

Set Input Focus on a Control Programatically Added to an ASP.Net Page

1/12/2007

Set Input Focus on a Control Programatically Added to an ASP.Net Page This little problem had the potential to drive me nuts for hours, I was fortunate to stumble over a blog with 100s of comments re problems of this nature and how to solve it. Most of the discussion was about using JavaScript, then I remembered I was using AJAX in my project and created a solution. '''The Problem''' I had a web page that automatically adds and removes TextBoxs based on a user's input e.g. a user may select "yes" in a DropDownList to a question and we need to get more information, so we add a Please Specify textbox on the postback of the DropDownList . But how on earth do you set the focus?? I tried adding the control to the page and then using its focus command, which didn't work. :-( '''Solution''' Luckly I was using Ajax on the page and I had a ScriptManager in the MasterPage. The script manager pumps out JavaScript, so I used a method on it to set the focus of the control using its client ID. This is the unique ID it is given on the page. Thank goodness for Google. I hope this helps you out..

Dynamically adding a CSS link to the page in c#

14/11/2007

Dynamically adding a CSS link to the page in c# The following code adds a CSS link to the header node of a Html page.

Preventing Caching of an ASP.net page in c#

5/11/2007

Preventing Caching of an ASP.net page in c# The following code prevents a page being cached.

Getting the Virtual Path of a Request in c#

5/11/2007

Getting the Virtual Path of a Request in c# This simple bit of code will get you the '''Virtual Path''' of your current request. Example Usage Notes Don't forget to include:

Fixing Form Action on UrlRewrite (UrlRewriter)

5/11/2007

Fixing Form Action on UrlRewrite IF you're rewriting URL's, you've probably come across the same problem I had. When posting back on the page, the real URL is used.. this is a real pain if you're writing a page which uses the '''RawUrl''' to serve up relevant content. I had a good look around the web for a solution. These ranged from creating a custom HtmlForm control to replacing the form tag in the App_Browsers folder. The following is simple and worked for me. Place the following code in the Page_Load of the page you're serving up. Hope this helps.

Custom Validators using Client Side JavaScript

2/11/2007

Custom Validators using Client Side JavaScript In my latest project I am really enjoying using the Ajax Control Toolkit, particularly the ModalPopupExtender. I've been using the popup panels to capture data, but I needed to validate the data that a user enters into certain fields. ASP.net's validators are the obvious choice, but when you have employed an AJAX control you need to validate the entry on the client's browser. This is easy to do using the '''ClientValidationFunction''' attribute of the validator. then create a JavaScript function to do the validation. Here I have created a Regular Expression to validate decimals. Then simply set the args.IsValid property to either true or false and return. In this example I have used the ScriptManager to write out a JavaScript variable ('''DiscountPercentageId''') with the ClientID of the ASP.net TextBox I'm validating. You'll also notice my GetElement function to handle the browser compatibility. I hope this proves useful in your next AJAXian web application. ;-)

Creating your first ASP.NET AJAX 1.0 Application

7/9/2007

Creating your first ASP.NET AJAX 1.0 Application Over the last year or so, AJAX has taken the web development world by storm. AJAX is short for Asynchronous JavaScript and XML and is an approach to building dynamic web applications that behave less like the static web pages we're used to and more like desktop applications. At the heart of AJAX is the XmlHttpRequest object, a component originally designed by Microsoft and used to provide the rich Outlook-like interface of Exchange Web Access. JavaScript on a web page can use an instance of XmlHttpRequest to send requests to the web server that generated the page and then use the response to update part of the page, without the browser having to reload everything. This can make the application a lot quicker -- instead of the entire page having to be transmitted and rendered, the browser just fetches what's needed to update the current page. Although the technologies that support AJAX-style web apps have been around for years, they weren't widely used until the introduction of frameworks that made dealing with the extra complexity, not to mention cross-browser differences, possible. {Microsoft's ASP.NET AJAX framework}http://ajax.asp.net/ is one of the most recent, and has just been released as version 1.0, following a year of pre-releases that used the code name "Atlas". This article shows you how to AJAX-enable an existing ASP.NET web page by using Microsoft's ASP.NET AJAX Extensions. The UpdatePanel control provided by the framework makes it really easy to start with AJAX programming by defining the areas of the page you want to update independently without a full page reload. Once you've understood the basics, you'll use an {InnerWorkings}http://www.innerworkings.com/ coding challenge that provides a sample AJAX-enabled bug tracking website to help you really understand how to use the AJAX Extensions. [[bugtracker.png]] What is Microsoft ASP.NET AJAX? Microsoft ASP.NET AJAX is a free framework designed to make it easier to write modern AJAX-style applications using ASP.NET. There are two parts to the framework -- a cross-browser JavaScript library and a set of server-side ASP.NET controls. The JavaScript library goes beyond simply enabling AJAX apps and provides object-oriented extensions to JavaScript to make it easier to write complex applications that need to process a lot of data in the browser. On the server-side, a set of new and enhanced ASP.NET controls make it possible to write AJAX applications by simply adding controls to a page, just as with non-AJAX applications. In fact, you don't have to write a single line of JavaScript to create a fully-featured AJAX application. As well as ASP.NET AJAX itself, there are two other downloads available to add AJAX functionality to your site. The {AJAX Futures CTP}http://www.microsoft.com/downloads/details.aspx?FamilyId=A5189BCB-EF81-4C12-9733-E294D13A58E6&displaylang=en (Community Technical Preview) is a collection of new features which will be added to the main AJAX Extensions framework in the future. The {AJAX Control Toolkit}http://www.codeplex.com/AtlasControlToolkit contains prewritten components like panels that can be dragged around the page and rating controls to enable users to submit feedback. What's an InnerWorkings Developer Coding Challenge? An InnerWorkings Developer coding challenge is a sample of code in Visual Studio that has a couple of key pieces missing. Each challenge includes selected reference links chosen specifically so you can easily find out how to fill in the blanks, complete the sample app, and learn about a new technology at the same time. Once you're finished, InnerWorkings Developer automatically checks your code so you can be sure you've solved the challenge correctly and that you really understand what you've learned. The coding challenges are designed to take you to the heart of the technology you want to learn more about, focusing on the most important, practical features. Because everything has been set up for you, you can dive straight in and start coding. InnerWorkings Developer has a library of hundreds of challenges on topics from ASP.NET to Windows Communication Foundation. For more information, have a look at our {catalog}http://www.innerworkings.com/catalog . How Does the UpdatePanel Work? The UpdatePanel is designed to be the easiest possible way to AJAX-enable your site, focusing on the most important feature of AJAX: restricting updates to an area within a page instead of requiring a full refresh. Although it completely changes how requests are made by the browser, the UpdatePanel is written in such a way that your pages execute normally, which means you don't have to rewrite any controls or server-side logic. As the browser loads the AJAX framework, a JavaScript onsubmit handler is added to every form element on the page. When the form submits, the handler checks whether this should be a "partial update" -- one handled by an update panel. If so, it collects all the data being sent to the server, repackages it, and sends it, not as a regular browser request, but using the XmlHttpRequest object. In the browser, the onsubmit handler now returns false, effectively telling the browser to cancel the full page refresh. Meanwhile, the request has made its way to your web server looking just like a normal request with one difference: an extra HTTP header lets the AJAX infrastructure know that this is a partial update. The page executes as normal and the output is collected ready to be sent to the browser. Just before it's sent however, another bit of AJAX magic kicks in. Everything that isn't needed for the UpdatePanel is stripped out and some extra data is sent (including updated hidden fields and ViewState for controls not included in the UpdatePanel). When this arrives back at the browser, the JavaScript library updates everything, including the contents of the UpdatePanel, but also all the extra data. If your ASP.NET page updates the page title or even the page's CSS styles, all of these are updated automatically. Using the UpdatePanel Despite all this automatic support, using the UpdatePanel couldn't be simpler. There's a little install work -- once the AJAX extensions are installed, there are only a couple of additions to your web.config file to paste in. (The easiest way to add these is simply to copy the sample config file which should be installed to C:\Program Files\Microsoft ASP.NET\ASP.NET 2.0 AJAX Extensions\v1.0.61025\web.config or somewhere similar, depending on where you installed the extensions.) After that you can AJAX-enable your website by adding just two tags to your webpage: a ScriptManager and the UpdatePanel itself. The ScriptManager control manages the AJAX JavaScript libraries and writes