Is it possible to create validation controls in a code behind file?

Posted on 2006-07-14
Last Modified: 2010-08-05
I want to use ASP.NET 2.0 validation controls. However, I don't want to place the validation tags (ie: <asp:RequiredFieldValidator ID="valFirstName" runat="server"></asp:RequiredFieldValidator>) in my aspx file. I want to create validator objects in my code behind file to keep my validation seperate and tidy.

I've tried placing the following code in the page load event, but the Validate() method throws an error (System.NullReferenceException: Object reference not set to an instance of an object.).

Dim valFirstName As New UI.WebControls.RequiredFieldValidator()
valFirstName.EnableClientScript = False
valFirstName.ControlToValidate = "txtFirstName"

Is this possible? How can I do it? Or am I stuck placing the asp tags in my aspx file?

Question by:graphicodyssey
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 2

Accepted Solution

pallosp earned 500 total points
ID: 17106721
You should add the validator to the page, e.g. Form.Controls.Add(valFirstName);
LVL 27

Expert Comment

ID: 17107696
>>I want to create validator objects in my code behind file to keep my validation seperate and tidy.
Any control you create in code behind will have to render its HTML, there is no way to have it seperate since all controls have to be added to aspx page.
what you can do is write code "No Validatation controls" and validate on the server side.


Author Comment

ID: 17113349

That worked like a charm.

I see that if I enable client-side scripting, it still creates the client-side script and validates fine. I'm wondering if there's any way to bind the validation control to say a text control to display the error message via the JavaScript. Is this possible?

PeopleSoft Has Never Been Easier

PeopleSoft Adoption Made Smooth & Simple!

On-The-Job Training Is made Intuitive & Easy With WalkMe's On-Screen Guidance Tool.  Claim Your Free WalkMe Account Now


Author Comment

ID: 17113389
By the way, in the rendered HTML I see that it creates the span/div tag, but it places it right before the closing </form> tag. I'm assuming it does this since it doesn't know where else to go. So... is there any way to tell it to go somewhere else?

Author Comment

ID: 17113487
I was able to answer my own question. I added a PlaceHolder control to the page and then was able to add the validation control to the placeholder control programmatically, thus allowing me to place the validation text anywhere on the page. If there's a better way to do this, please let me know, otherwise thanks for your help!

Expert Comment

ID: 17113963
You don't need a PlaceHolder. The validator can be inserted at a particular position by a Form.Controls.AddAt() call, if you know the exact position.
However it's easier to determine the position of the message by a PlaceHolder.

Author Comment

ID: 17115735
Even better! Thank you for pointing that out.

I create a subroutine to find the index of the field I wanted to validate and then used the AddAt method to place the validator. This is EXACTLY what I wanted to do. Thanks again.

Featured Post

Salesforce Has Never Been Easier

Improve and reinforce salesforce training & adoption using WalkMe's digital adoption platform. Start saving on costly employee training by creating fast intuitive Walk-Thrus for Salesforce. Claim your Free Account Now

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

User art_snob ( encountered strange behavior of Android Web browser on his Mobile Web site. It took a while to find the true cause. It happens so, that the Android Web browser (at least up to OS ver. 2.…
Problem Hi all,    While many today have fast Internet connection, there are many still who do not, or are connecting through devices with a slower connect, so light web pages and fast load times are still popular.    If your ASP.NET page …
There's a multitude of different network monitoring solutions out there, and you're probably wondering what makes NetCrunch so special. It's completely agentless, but does let you create an agent, if you desire. It offers powerful scalability …
If you’ve ever visited a web page and noticed a cool font that you really liked the look of, but couldn’t figure out which font it was so that you could use it for your own work, then this video is for you! In this Micro Tutorial, you'll learn yo…

623 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question