Arnold Matusz's Blog

Most .NET developers write their code in a Visual Studio IDE. There are several reasons to use Visual Studio, but only few people really explore more advanced features than the basic controls / windows: Solution Explorer, Class View, Model Browser, Toolbox, Find and Replace :).

This is why I' ld like to take the opportunity to write about Visual Studio Macros for those of you who haven't had the chance meet Macros until now. » Continue reading ...

Lately I’ve come across an interesting situation involving BlogEngine.Net. I normally use Windows Live Writer to write my blog posts, and as I really love to post some programming related articles I use Syntax Highlighter. Sadly I don’t have Windows Live Writer set up (with all the plugins) on each workstation I work on, so whenever I need to change something in a post (typos, updates, etc.) and WLW is not at hand I get down and dirty and edit the XML files which the posts are saved in.

I hear you asking: Why you stupid idiot are you doing that when you can edit your posts in a nice WYGIWYS editor? Well, the only reason is that when I post code samples those need to be in pre tags where each and every space i very important. And after I edit/save a post in BE’s (online) the formatting is lost. » Continue reading ...

In my post about LINQ to XML - XPath I've mentioned how Microsoft warns about the performance bottleneck when using LINQ to XML with the Extension class from the System.Linq.XPath namespace.

"There is some performance penalty for using these methods. Using LINQ to XML queries yields better performance. So it is only advisable to use such LINQ to XML with XPath queries if and only if your application won't suffer from the slight loss of performance!"

The scenario: I’ve been using Visual Web Developer 2008 for a web application and after I moved the application from the inbuilt ASP.NET Development Server to IIS I encountered the following exception message:

Failed to map the path '/App_GlobalResources/'

There are a few blog posts out there which may apply to your case, especially if you have Crystal Reports 8 installed. Worth mentioning is: www.thejoyofcode.com. If your situation is proior to Visual Studio 2008 you might find your solution immediately in the blog content, but if the concern is a bit newer reading through each comment might be helpfull. » Continue reading ...

LINQ to Entities does not recognize the method 'Int32 ToInt32(System.String)' method, and this method cannot be translated into a store expression.

This is a shortcomming of LINQ to Entities, and indeed the ADO.NET Entity Framework at the current release! The reason for a similar exception message is that in queries on the Entity Framework, custom methods and extensions methods cannot be translated into store expressions.

There are workarounds to still enjoy LINQ to Entities and as an example please read the following: » Continue reading ...

Although the ModalPopupExtender isn’t new at all there are still countless poeple who search the web for a comprehensive sample on how a ModalPopupExtender is used from a GridView.

First of all you’ld need to have a Button in each row which should trigger the ModalPopupExtender, then you would need to have an instance of a ModalPopupExtender with the TargetControlID set to the ID of that Button. » Continue reading ...

First of all it's worth mentioning that Microsoft brought enhancements to the ASP.NET AJAX Extensions. Now we can use a History control which allows us to use the back button to navigate back to a state before the last async postback happened.

Then there is Dynamic Data which is a framework that discoveres the data model and determines the UI which is best suited, dynamically, during runtime. This sounds weird but it can be of big help! Ex: When you try to display a DateTime value in a GridView, you can use a <asp:DynamicField ... /> which will automatically print your DateTime value nicely formatted. To achieve this with the Normal <asp:BoundField ... /> you needed to set HtmlEncode="false" and DataFormatString="{0:D}". If your DataField is a simple string, this will render a LiteralControl. Not only do these work in Read-Only mode, this also happens in Edit mode which can big of big help. » Continue reading ...

Restricting the user from leaving certain fields blank is often mandatory, because we don't want to have empty fields in our database, or we may want the user to specify exactly how many products he wishes to order. Asp.net comes in really good here with the Validation Controls. For my example the RequiredFieldValidator is perfectly suited because it displays a little error message for the control it validates.

All is fine until you have 40-50 fields that have to be filled out. In this case it's of good practice to use the ValidatioSummary control which summarises all the error messages from the ValidationGroup and shows them either in text on the page or as a Javascript alert().  » Continue reading ...

Web development with Asp.net is very fast. We have drag and drop controls with out of the box functionality. This concept of prebuild controls is of huge advantage when it comes to rapid application development, saving us allot of time ... but there is one major drawback. We are normally limited to what the controls offer in: rendering, functionality, etc.

Microsoft controls normally render table based designs, which are very difficult to style. If you want to override this you can achieve it using CssFriendlyControlAdapters. It's the same case for the TreeView Control but the table based rendering is probably not the thing that bothers me the most! » Continue reading ...

While writing a short piece of code for my global exception handling post I figured out a nice fact. What I wanted to achieve is to have redirection to a custom error page which displays exception details. This can be easily done by using Response.Redirect() (to ex: ~/exception.aspx"), but this will completely lead to another page. This is not usefull if I'm interested in the actual URL where the exception has been thrown. (ex: ~/products.aspx?catid=4&pageid=7 ..."). By using Response.Redirect() you end up with "/exception.aspx" as the URL in the browser.

An obvious solution at first sight is ... we need to use Server.Transfer() which won't create a new Context (i.e.: the url in the browser will stay the same but we show the contents of a completely new page). And of course this is all fine ... until you need to use this functionality in an ASP.NET AJAX enabled website in an UpdatePanel.

By calling Server.Transfer() during an asynchronous postback the following alert will be displayed:

Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed. Common causes for this error are when the response is modified by calls to Response.Write(), response filters, HttpModules, or server trace is enabled.

Details: Error parsing near '

<!DOCTYPE html P'.

The reason why you can't use a Server.Transfer() in an UpdatePanel is more and more obvious when you think about what AJAX is. We only request small pieces of markup which replace little portions of a page, the whole point of AJAX is to avoid downloading the whole page again. This means that when triggering an async postback, the PageRequestManager expects to receive some small portion of HTML, but because the Server.Transfer() call was made the actual response is the markup for a completely new/different page (which begins with the DOCTYPE definition, this is what you can see at the end of the exception message).

If you decide to use a Server.Transfer() in an UpdatePanel you can avoid this exception by setting your Trigger to a PostBackTrigger. (i.e. The control which fires the method where Server.Transfer() is called won't cause an async postback!).
» Continue reading ...