Dynamically populating a DropDownList, AutoPostback and JavaScript error

[user1980]

hello,

i am trying to create a request form using asp.net where when a user selects a checkbox, a dropdown should appear dynamically. I have seen few java-scripts in web, but I was wondering if I can achieve this without java-script.

I tried to make the control invisible(<asp: DropDownList ID="DropDownLis t1" runat="server" AppendDataBound Items="True" Visible="False">) and in the onselectedindex changed event, tried to make the invisible property to true. But it did not help me.
Also, I was trying to use postback for the page when a checkbox is selected(asp:Ch eckBoxList ID="chckbx" runat="server" AutoPostBack="t rue" onselectedindex changed="chckbx _SelectedIndexC hanged") and it throws me an error in IE saying the object does not support this property.


Can somebody please help me with this. Thanks in advance.

[Frinavale]

Before you continue please take a look at this article on:
How to use dynamic controls in ASP.NET.

-Frinny

[user1980]

thank you for the reply.

I am able to understand the example in the link but could not really put it into working for my scenario.

[Frinavale]

Ok, in your scenario you need to do this when the user checks a checkbox.
I'm assuming that you need to populate the drop down list with items depending on what the user has checked.

This is not dynamically creating a control.

What you need to do is dynamically populate the drop down list.

What do you have currently that we can use as a starting point?

-Frinny
(PS please post code in code tags)

[user1980]

Yes, I have to populate the dropdown based on the selection of checkbox.

Here is my information. I have four sources of information as checkboxes, newspapers,web, employee and others. Now when a user checks newspapers, the dropdown must populate, tribune,WSjourn al,PJ star.

And one more thing is if I put the autopostback ppty for checkbox to true, it throws me an error. This should be something very basic, am I missing something?
Thanks for all your help.

[Frinavale]

Lets fix the error because you need to set the checkBoxList's autopostback=tr ue.
Please post the error details.

-Frinny

[user1980]

the error appears only in IE, as a script error. I mean the page loads normally but on the left hand bottom corner, it says there is an error on the page. When i click on it, it tells me the the object does not support this property or method.
When I try to debug the page without the autopostback property, it does not display any error.

[Frinavale]

Do you have any additional JavaScript on the page?

-Frinny

[user1980]

yes, a one line javascript to open a pop-up window.

[Frinavale]

Post that code please.

-Frinny

[user1980]

function window_open()
      {
       window.open("Codes.aspx","","menubar=no,status=no,scrollbars=yes,resizable=yes,toolbar=no,top=180,left=250,width=750,height=600");
      }

the ap.net control that calls it,

<asp:Button runat="server" ID="btnlookup" Text="Code" OnClientClick="window_open()" CausesValidation="false" Width="90px" />

[Frinavale]

I don't see anything wrong with this JavaScript.
I'm going to ask that a JavaScript expert take a look at this.

Does this problem prevent your code from being executed?
If so, could you remove it while we are fixing your current problem with dynamically populating the DropDownList?

-Frinny

[Dormilich]

I'm going to ask that a JavaScript expert take a look at this.

I can’t find anything wrong, works as expected when inserted in plain text HTML.

[user1980]

my page executes normally. but I just wanted to get rid of the error and also wanted to postback the page when I check the checkbox.

[Frinavale]

Well enable autopostback for the checkbox.
Put a break point on the method that handles the event and run the application.
Do you hit the break point?

-Frinny