Question

I have a custom usercontrol, which is basically a dropdownlist, prepopulated with values from the database.

<asp:DropDownList ID="selResponseTimes" runat="server" SkinID="filterSkin">                
</asp:DropDownList>

Code behind:

public partial class Response_Times_Drop_Down : System.Web.UI.UserControl
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DataTable objDataTable = DAL.ExecuteDataTable("sp_cl_Response_Times_Get", null);
            selResponseTimes.DataSource = objDataTable;
            selResponseTimes.DataTextField = "TM_Code";
            selResponseTimes.DataValueField = "TM_Code";
            selResponseTimes.DataBind();
        }
    }

    public string SelectedValue
    {
        get
        {
            return selResponseTimes.SelectedValue;
        }
        set
        {
            selResponseTimes.SelectedValue = value;
        }
    }

}

The control is added to my page as follows, and works fine:

<asp:ResponseTimesDropDown runat="server" ID="selResponse" />

I’m adding client side events as attributes to standard controls on Page_Load using the following:

txtCallRelatedCall.Attributes.Add("onblur", "CheckRelatedCall()");

However, when I attempt to do this with my custom control they are not being added.

selResponse.Attributes.Add("onchange", "CalculateResponseTime()");

However if I debug the code, the attributes are being added to the collection, it appears that they are just not being output to the page. Why is this?

Answer 1

In what stage of the page lifecycle are you adding the attributes?

Try adding them in on Page_Init

Protected void Page_Init(object sender, EventArgs e)
{
    selResponse.Attributes.Add("onchange", "CalculateResponseTime()");
}

EDIT (See Comments):

Public void CalculateResponseEnabled()
{
        selResponseTimes.Attributes.Add("onchange", "CalculateResponseTime()");
}

Then in the from you can call CalculateResponseEnabled by doing.

selResponse.CalculateResponseEnabled();