Question

I have a dropdown list in User Control

How Can I get selected value of dropdown list of user control in page when user select another item (auto postback is true)?

I tried to store selected value of ddl in a public member from Selected Index Changed event handler. But this handler executes after page load of container page. I need to load data in page based on selected value in ddl of user control.

Thanks

User Control’s code

protected void ddlPageSize_SelectedIndexChanged(object sender, EventArgs e)

{

        _SelectedPageSize = Convert.ToInt32(ddlPageSize.SelectedValue);

}



int GetSelectedPageSize()

{

       return _SelectedPageSize;
}

Answer 1

There are a number of ways to accomplish what you’re looking for. The first is simply to re-order your events in the containing page. If you use the PreRender event rather than the PageLoad event, your drop down selection action will be complete and the information will be readily available.

A second method, which probably more extensible, would be to raise a custom event from your usercontrol that your page listens for and handles. Then the action would be taken directly at the point where the information is immediately available. This allows any containing structure (whether it’s a page, usercontrol or something similar) to subscribe to the event and handle whatever is needed.

A third method, a little more rigid, would be to have a function in the containing page that is called by the usercontrol once the data is complete. This requires the usercontrol to have knowledge of the specific page type that it will be included in (making it less extensible) so I wouldn’t recommend it.

Edit: Here’s an idea for implement option #2 with a custom event:

public partial class MyUserControl: UserControl
{
    //All of your existing code goes in here somewhere

    //Declare an event that describes what happened. This is a delegate
    public event EventHandler PageSizeSelected;


    //Provide a method that properly raises the event
    protected virtual void OnPageSizeSelected(EventArgs e)
    {
        // Here, you use the "this" so it's your own control. You can also
        // customize the EventArgs to pass something you'd like.

        if (PageSizeSelected!= null)
            PageSizeSelected(this, e);
    }

    private void ddlPageSize_SelectedIndexChanged(object sender, EventArgs e)
    {
        _SelectedPageSize = Convert.ToInt32(ddlPageSize.SelectedValue);
        OnPageSizeSelected(EventArgs.Empty);
    }
}

Then in your page code you would listen for the event. Somewhere in the page load you would add:

myUserControlInstance.PageSizeSelected += MyHandinglingMethod;

And then provide the method that handles the event:

protected void MyHandlingMethod(object sender, EventArgs e)
{
    // Do what you need to do here
}