Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

Enable event validation with AJAX cascading drop downs

Posted on 2010-11-10
6
Medium Priority
?
1,008 Views
Last Modified: 2012-05-10
My question is regarding the solution on this page http://www.experts-exchange.com/Programming/Languages/C_Sharp/Q_25373688.html

I have implemented the solution but when I try to reference the controls after a postback they are not available.

Eg.
 
   Protected Sub bSearch_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles bSearch.Click

       ....

       If nvddl1.SelectedValue <> "" Then id = nvddl1.SelectedValue
       ....

    End Sub

Gives the error Object reference not set to an instance of an object.

Thanks,
Karen
0
Comment
Question by:KarenMcC
[X]
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
  • 3
  • 3
6 Comments
 
LVL 96

Expert Comment

by:Bob Learned
ID: 34111889
What is Nothing (nvddl1 or SelectedValue)?  How are you binding the CascadingDropDown?  Is is a dynamic or static control?
0
 

Author Comment

by:KarenMcC
ID: 34115471
nvddl1 is nothing.

This is example code:

    Private nvddl1 As NoValidationDropDownList
    Private nvddl2 As NoValidationDropDownList
    Private cdd1 As AjaxControlToolkit.CascadingDropDown
    Private cdd2 As AjaxControlToolkit.CascadingDropDown

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        nvddl1 = New NoValidationDropDownList()
        nvddl1.ID = "nvddl1"
        ph1.Controls.Add(nvddl1)

        cdd1 = New AjaxControlToolkit.CascadingDropDown()
        cdd1.ID = "cdd1"
        cdd1.TargetControlID = "nvddl1"
        cdd1.Category = "country"
        cdd1.ServicePath = "~/RegionService.asmx"
        cdd1.ServiceMethod = "GetCountries"
        cdd1.SelectedValue = 4
        ph1.Controls.Add(cdd1)

        nvddl2 = New NoValidationDropDownList()
        nvddl2.ID = "nvddl2"
        ph1.Controls.Add(nvddl2)

        cdd2 = New AjaxControlToolkit.CascadingDropDown()
        cdd2.ID = "cdd2"
        cdd2.TargetControlID = "nvddl2"
        cdd2.ParentControlID = "nvddl1"
        cdd2.Category = "region"
        cdd2.ServicePath = "~/RegionService.asmx"
        cdd2.ServiceMethod = "GetRegionsForCountry"
        ph1.Controls.Add(cdd2)


    End Sub

I would prefer to add the control in design, but do not know how to do that.

Thanks.
k.
0
 
LVL 96

Expert Comment

by:Bob Learned
ID: 34117640
Is NoValidationDropDownList your own custom extender/control?
0
Veeam Disaster Recovery in Microsoft Azure

Veeam PN for Microsoft Azure is a FREE solution designed to simplify and automate the setup of a DR site in Microsoft Azure using lightweight software-defined networking. It reduces the complexity of VPN deployments and is designed for businesses of ALL sizes.

 

Author Comment

by:KarenMcC
ID: 34118145
Yes...

Public Class NoValidationDropDownList
    Inherits DropDownList
End Class

The only purpose of this is so that the control is not validated by EnableEventValidation="true".
0
 
LVL 96

Accepted Solution

by:
Bob Learned earned 2000 total points
ID: 34119666
Is this a "custom control" or a "user control"?  If it is a custom control, I would create another control library project, put the custom control into the library, and create a project reference.  The Visual Studio.NET IDE should recognize this, and add the control to the tool box, so that you can drag and drop.
0
 

Author Comment

by:KarenMcC
ID: 34133037
Thanks very much. This works very well.
0

Featured Post

Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

Question has a verified solution.

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

Just a quick little trick I learned recently.  Now that I'm using jQuery with abandon in my asp.net applications, I have grown tired of the following syntax:      (CODE) I suppose it just offends my sense of decency to put inline VBScript on a…
User art_snob (http://www.experts-exchange.com/M_6114203.html) 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.…
Have you created a query with information for a calendar? ... and then, abra-cadabra, the calendar is done?! I am going to show you how to make that happen. Visualize your data!  ... really see it To use the code to create a calendar from a q…
Please read the paragraph below before following the instructions in the video — there are important caveats in the paragraph that I did not mention in the video. If your PaperPort 12 or PaperPort 14 is failing to start, or crashing, or hanging, …

618 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