Drilling down a nested master page in ASP.NET to reset a form

Here is an example of drilling down a master page in ASP.NET to reset a form's TextBox controls:

    protected void btnqReset_Click(object sender, EventArgs e)
    {

        try
        {
            ContentPlaceHolder childMasterContent = (ContentPlaceHolder)Page.Form.FindControl("ParentMasterContent").FindControl("ChildMasterContent");
            Control ctrlForm = childMasterContent.FindControl("upnlQueryMoreCriteria").FindControl("pnlQueryMoreCriteria");
            Control[] queryControls = { ctrlForm };
            for (int i = 0; i < 1; i++)
            {
                if (queryControls[i].Controls != null)
                {
                    foreach (Control ct in queryControls[i].Controls)
                    {
                        if (ct.GetType().ToString().Equals("System.Web.UI.WebControls.TextBox"))
                        {
                            ((TextBox)ct).Text = "";
                        }
                    }
                }
            }
        }
        catch (Exception ex)
        {
            log.Error("Unable to reset query criteria: " + ex.Message + ex.StackTrace);
            
        }
    } 

FindContol Solution to add Javascript to a control from a user control

Here is a great solution to finding a control using FindControl method from a user control. TargetcontrolID is the public property for TextBoxFooExtender (User Control). _txt is the targeted TextBox assuming it is found.

    protected override void CreateChildControls()
    {
        txt = (TextBox)this.Parent.FindControl(TargetControlID);
        if (txt != null) {
            _txt.Attributes.Add("ondblclick", "alert('foo')");
        }
        base.CreateChildControls();
    }

Implementing Dynamic Hyperlink of Current Page

Here's how to implement a dynamic HyperLink of the current page based on the current pages title and current URL without the query string parameters. This is located in the Master Page.

    protected void Page_Load(object sender, EventArgs e)
    {
        hlPageTitle.Text = Page.Title.ToString();
        // old way would fetch query string paramaters
        //hlPageTitle.NavigateUrl = Request.Url.AbsoluteUri.ToString();
        hlPageTitle.NavigateUrl = Request.Url.GetLeftPart(UriPartial.Path);
    }

Reference link.

Modifying labels in MasterPage From MasterPage user Page

First, here is how to modify a label in the MasterPage from the MasterPage user Page:

        Label mpLabel = (Label)Master.FindControl("lblPageTitle");
        if (mpLabel != null)
        {
            mpLabel.Text = this.Title.ToString();
        }

link