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6 Items, 1 Pages 1 |< << Go >> >|

	SteveC71
	Asp.Net User

Custom validation control

3/11/2005 4:49:59 PM

0/0

I am working on a form that has about 60 check boxes on the page. Each check box needs to be checked before the form can be submitted. After getting the form designed I ran into the problem that Microsoft's validation controls do not allow validation of a check box. I searched the net for hours looking for an example and located a project that validates a checkbox list but not a single check box and worse for me it was in C# and I mainly use VB.NET. I found a C# to VB.NET converter and then modifed the code to as follows:



Imports System


Imports System.Text


Imports System.Web.UI


Imports System.Web.UI.WebControls


Namespace Validators


    Public Class RequiredFieldValidatorForCheckBoxes


        Inherits BaseValidator


        Protected Overrides Function ControlPropertiesValid() As Boolean


            'This allows us to enter checkbox control without getting an error.


            Return True


        End Function 'ControlPropertiesValid


        Protected Overrides Function EvaluateIsValid() As Boolean


            Return Me.EvaluateIsChecked()


        End Function 'EvaluateIsValid


        Protected Function EvaluateIsChecked() As Boolean


            Dim _chk As CheckBox = CType(Me.FindControl(Me.ControlToValidate), CheckBox)


            If _chk.Checked = True Then


                Return True


            Else


                Return False


            End If


        End Function 'EvaluateIsChecked


        Protected Overrides Sub OnPreRender(ByVal e As EventArgs)


            If Me.EnableClientScript Then


                Me.ClientScript()


            End If


            MyBase.OnPreRender(e)


        End Sub 'OnPreRender


        Protected Sub ClientScript()


            Me.Attributes("evaluationfunction") = "cb_vefify"


            Dim sb_Script As New StringBuilder


            sb_Script.Append("<script language=""javascript"">")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("function cb_vefify(val) {")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("var val = document.all[document.all[""")


            sb_Script.Append(Me.ID)


            sb_Script.Append("""].controltovalidate];")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("var col = val.all;")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("if ( col != null ) {")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("for ( i = 0; i < col.length; i++ ) {")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("if (col.item(i).tagName == ""INPUT"") {")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("if ( col.item(i).checked ) {")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("return true;")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("}")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("}")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("}")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("return false;")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("}")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("}")


            sb_Script.Append(ControlChars.Cr)


            sb_Script.Append("</script>")


            Me.Page.RegisterClientScriptBlock("RBLScript", sb_Script.ToString())


        End Sub


    End Class


End Namespace

The code compiles and I was able to build the DLL and import it into VS but no matter what I do the control ends up firing as not valid and displays the error message associated with it. I'm pretty much at a loss here as to what I have done wrong. Can some point out my mistake(s)?

Thanks
Stephen

	plblum
	Asp.Net User

Re: Custom validation control

3/11/2005 10:01:51 PM

0/0

Since you only wrote client-side evaluation, you need to look at and debug the JavaScript output. You've shown us the serve side code generator. But what does it output? Visual Studio.net has a debugger which lets you set up breakpoints into the javascript that is output to your web form. Use it to debug this problem.

You *must* write validation on the server side too. Not because its required by ASP.NET but because you have to assume your client-side validation code will not run. Microsoft's validators only support validation on DHTML browsers like IE and IE/Mac. Even those browsers allow turning off javascript. Finally, hackers can exploit the exposed javascript to work around your defenses.

FYI: I rewrote validation for ASP.NET with Professional Validation And More. The original validation system has so many limitations (which you are hitting) that force you to write custom code. I've built a system based on what users have requested. It includes 22 validators that all support client-side validation on IE, IE/Mac, Netscape 7, Mozilla, FireFox, Opera 7 and Safari.
In your case, you will use my CountTrueConditionsValidator. It is designed to detect how many checkboxes are marked. In your case, you need to confirm one or more is marked. It generates the javascript and handles server side validation too.
I also have a checkbox validator. It includes a utility to quickly convert a page to my validators.

--- Peter Blum
Creator of Professional Validation And More Suite, Peter's Date Package, and Peter's Polling Package
www.PeterBlum.com

	SteveC71
	Asp.Net User

Re: Custom validation control

3/11/2005 11:41:07 PM

0/0

Peter,

Thank you for the reply. Apparently I am not understanding what I trying to do with this control.



        Protected Overrides Function EvaluateIsValid() As Boolean





            Return Me.EvaluateIsChecked()





        End Function 'EvaluateIsValid





        Protected Function EvaluateIsChecked() As Boolean





            Dim _chk As CheckBox = CType(Me.FindControl(Me.ControlToValidate), CheckBox)





            If _chk.Checked = True Then





                Return True





            Else





                Return False





            End If





        End Function 'EvaluateIsChecked

In the code above I believed I was doing the server-side validation. I'm not sure where to turn next at this point. I don't believe that writing the code to do what I want is beyond my comprehension. I have to believe that I can accomplish writing this control.

Can you suggest any sites or books that might lead me in the direction I need to head so that I can complete this control. I want to learn so any help you can provide would be greatly appreciated. My target audience will only be using IE.

Thanks,
Stephen

	plblum
	Asp.Net User

Re: Custom validation control

3/12/2005 5:34:33 PM

0/0

The call to Page.RegisterClientScriptBlock is a dead giveaway that you are writing client-side code (as it a function called ClientScript).

The only good docs I've found on validation is in the .net documentation.

I'm not sure why you are not interested in solving this through a solid and well-liked replacement to Microsoft's validation framework that only costs $100. You could download it, set it up, and move on to the task of delivering your web site. The reason I keep pointing this out is that as an expert in ASP.NET validation, I know how primitive the tools you have now really are. In fact, I put together a list of all of the issues I've found here to educate users. Microsoft may write nice things but not every webcontrol is feature rich enough to address even common situations and you are proving it by spending a lot of time researching and writing code. Believe me, your situation is very common and that's why I built a validator for it.

--- Peter Blum
Creator of Professional Validation And More Suite, Peter's Date Package, and Peter's Polling Package
www.PeterBlum.com

	SteveC71
	Asp.Net User

Re: Custom validation control

3/14/2005 12:57:10 PM

0/0

The reason for my interest in solving this problem is the same reason for my interest in programing to begin with. I want to learn. Second I am working on this project with $0 budget. I'm trying to make a part of my job easier. Third I want to figure this out now mainly because the only answer I have recieved is "HERE BUY THIS". I'm sure your controls are great and thanks for your insight on this issue. I'm off to the .NET documentation to start my research on how I am going to figure this one out. Until then I will just change my form to utilize a text box and make the person filling out the form type yes.

Thanks,

Stephen

	SteveC71
	Asp.Net User

Re: Custom validation control

3/14/2005 1:30:06 PM

0/0

Just an FYI that when I removed the ClientSide script the control acted exactly as I expected. I have no need for client side script in my project as the volume of the submitted form will be fewer than 10 a day. Again thanks for your guidance on the documentation, a quick read of it got this working for me.

Thanks,

Stephen

6 Items, 1 Pages 1 |< << Go >> >|

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