How to get value from dynamic control in update panel

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I have given code for adding dynamic Control below , how to get value from this

C#

DropDownList ddlAgent = new DropDownList();
                    ddlAgent.EnableViewState = false;
                    ddlAgent.CssClass = "RegsSelect";
                    ddlAgent.ID = "ddlAgent";
                    ddlAgent.ClientIDMode = ClientIDMode.Static;
                    ddlAgent.Attributes.Add("style", "margin-left:-4px;height:40px;width:328px;");
                    upText.ContentTemplateContainer.Controls.Add(ddlAgent);

                    //Binding data with dropdownlist
                    CUser objUser = new CUser();
                    ddlAgent.DataSource = objUser.GetUserByRoleId(4);
                    ddlAgent.DataValueField = "Id";
                    ddlAgent.DataTextField = "FirstName";
                    ddlAgent.DataBind();

now to get control

C#

DropDownList ddlAgent=(DropDownList) upText.ContentTemplateContainer.FindControl("ddlAgent");

which gives Null Reference Exception

it is created from selected index of previous dropdownlist and it is placed in updatepanel

Posted 5-May-13 22:23pm

Jigar Sangoi

Updated 5-May-13 22:43pm

v2

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_Amy · Answer 1 · 2013-05-05T22:35:00

Always create your dynamic control in Page_Init event (Read this[^] and this[^] for a detailed information).
Change your CS. Try this:

C#

//Create the controls in this page event
protected void Page_Init(object sender, EventArgs e)
{
    DropDownList ddlAgent = new DropDownList();
    ddlAgent.EnableViewState = false;
    ddlAgent.CssClass = "RegsSelect";
    ddlAgent.ID = "ddlAgent";
    ddlAgent.ClientIDMode = ClientIDMode.Static;
    ddlAgent.Attributes.Add("style", "margin-left:-4px;height:40px;width:328px;");
    upText.ContentTemplateContainer.Controls.Add(ddlAgent);
}

Now, find the control and bind it in your function or method. Try this:

C#

DropDownList ddlAgent=(DropDownList) upText.ContentTemplateContainer.FindControl("ddlAgent"); //Now you won't get a null referance exception
//Binding data with dropdownlist
CUser objUser = new CUser();
ddlAgent.DataSource = objUser.GetUserByRoleId(4);
ddlAgent.DataValueField = "Id";
ddlAgent.DataTextField = "FirstName";
ddlAgent.DataBind();

--Amit