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Syntax Change When Building Controls Dynamically in ASP.NET 2.0

, 19 Apr 2006
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From ASP.NET 1.x to ASP.NET 2.0 there has been a fundamental syntax change that applies to building server-side controls dynamically.

Introduction

This tiny snippet will attempt to save developers that are porting ASP.NET 1.1 code to ASP.NET 2.0 code. Especially if controls are being built dynamically.

Using the code

The code posted here should replace any legacy ASP.NET code when converting to ASP.NET 2.0 if you are building server-side controls dynamically. It can even be a find and replace but not doing it will cause those controls to not pick up the correct values out of them.

Below is how I retrieved a value from an ASP.NET server control that was built on the fly or dynamically using VB.NET 2003.

Request.Form(me.ClientID & ":controlname")

The above code snippet will not work in Visual Studio 2005. There is no error thrown but the value property of the control returns nothing when there is a valid value available. This makes this little issue hard to catch without unit tests. Below I have included the same line of code as before but with one fundamental difference. The ":" gets replaced by "$".

Request.Form(me.ClientID & "$controlname")

This fixes the issue for ASP.NET 2.0. I did not see any documentation on this so I hope this is useful to someone.

License

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About the Author

bholliman
Web Developer
United States United States
I am the lead software architect for Benefit Communications Inc. based in Nashville, TN. I specialize in enterprise development for windows and the web using .NET and IVR (Interactive Voice Response) systems. I hold the MCSD and MCDBA. I have a passion for video production. I love everything from shooting the video to editing it and everything in between. I love new technology and spend a lot of time on Microsoft's Research website. I am also very interested and amazed at the potential power of nanotechnology.

Comments and Discussions

 
QuestionDid you already try to use me.UniqueID instead? Pinmemberptmcomp19-Apr-06 10:31 
AnswerRe: Did you already try to use me.UniqueID instead? Pinmemberbholliman19-Apr-06 10:44 
GeneralRe: Did you already try to use me.UniqueID instead? Pinmemberptmcomp19-Apr-06 10:58 
GeneralRe: Did you already try to use me.UniqueID instead? Pinmemberbholliman19-Apr-06 11:38 
GeneralRe: Did you already try to use me.UniqueID instead? [modified] Pinmemberbreischl13-Jul-06 6:53 
Actually ClientID is slightly different, it uses yet another delimiter that's more friendly for Javascript.
 
So under 1.1, a control might have these IDs:
UniqueID: logindialog:chkPersist
ClientID: logindialog_chkPersist
 
And under 2.0, it would be like this:
UniqueID: logindialog$chkPersist
ClientID: logindialog_chkPersist
 
The UniqueID gets used for the HTML name attribute, so that's what the form value will be available as. The ClientID is only useful for clientside scripting code (ie, Javascript)
 
-- modified at 12:08 Thursday 13th July, 2006
I forgot to mention, we've noticed that the delimiter used in UniqueID seems to change based on the environment. On all our dev machines it still uses a colon, but on the Win2k3 test servers it uses a dollar sign. We really don't know why that is. My guess is that it's something to do with IIS 5.1 vs IIS 6.0, but that's just a guess....
 
Best of luck,
BKR

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