CODEWITHSUNDEEP
asp.netautopostback
James
James

Reputation: 187

Asp.NET dropdownlist autopostback

I have a dropdownlist with autopostback enabled. and have a repeater where i populate checkboxes from database.

If i set the autopostback to true then when selecting a value checkboxes lose its value...

Any workarounds on this?

Here is the code : 

<asp:DropDownList ID="dropdown" runat="server"  class="pop" AutoPostBack="true" >
</asp:DropDownList>

<asp:Repeater ID="rptD" runat="server" >
        <ItemTemplate>
        <td valign="top" >
        <input type="checkbox" class="al" />
        </ItemTemplate>
        </asp:Repeater>

Upvotes: 0

Views: 6477

Answers (2)

Tim Schmelter
Tim Schmelter

Reputation: 460108

I assume this is because you are DataBinding the Repeater not only if(!IsPostBack) but also on postbacks. Therefore the checked state will be overriden.

So do this in Page_Load(assuming C#):

if(!IsPostBack){
   DataBindRepeater();
}

Whereas DataBindRepeater is a method that sets the DataSource property and DataBind the Repeater.

You might also want to use an ASP.NET Checkbox control instead of the html input type="checkbox". The checked state is reloaded only if it's a server WebControl that implements IPostBackDataHandler.

Upvotes: 4

David
David

Reputation: 218827

This sounds indicative of populating the checkboxes in Page_Load. Is that the case? If you're populating the controls in Page_Load then you'll want to wrap it in a conditional:

if (!IsPostBack)
{
  // populate your controls from data
}

Otherwise, they'll get re-populated with each postback. When you have an autopostback or click a button or perform some other action on the page which initiates a postback, Page_Load is called before the event handler. So in effect, this is happening:

  1. User navigates to the page
  2. Page_Load clears and populates the checkboxes
  3. User chooses an item in the DropDownList (triggering a postback)
  4. Page_Load clears and populates the checkboxes
  5. DropDownList autopostback handler is called

(On a side note... Please look into using AJAX for dynamic client-server interaction like this. Autopostback makes for a poor user experience, and as you're discovering also makes for a difficult development experience.)

Upvotes: 1

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