I have a gridview showing some data—naturally. One of the columns is a template field that contains a Hyperlink.  As part of my rowdatabound processing, I would like to add to the querystring for that row's url.  Unfortunately, I haven't been able to target the control yet. 
 

My latest attempt is:

 ((HyperLink)e.Row.Cells[1].Controls[0]).NavigateUrl += "&missing_info=account";

 This causes a runtime error:

Unable to cast object of type 'System.Web.UI.LiteralControl' to type 'System.Web.UI.WebControls.HyperLink'.

 
I tried targeting the TemplateControl.Controls[0] as well, but got the same result.  Here is my gridview, any ideas?

<asp:GridView ID="clients_gridview" runat="server" AutoGenerateColumns="False"
                DataSourceID="LinqDataSource1" AllowSorting="True"
                onrowdatabound="GridView1_RowDataBound">
                <Columns>
                    <asp:boundfield DataField="GroupCode" HeaderText="Group #"
                        SortExpression="GroupCode"></asp:boundfield>
                    <asp:templatefield HeaderText="SSN" SortExpression="SSN">
                        <ItemTemplate>
                            <asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='test.asp?ssn=<%# Bind("SSN") %>' Text='<%# Bind("SSN") %>'></asp:HyperLink>
                        </ItemTemplate>
                    </asp:templatefield>
                    <asp:templatefield HeaderText="Client Name" SortExpression="LastName">
                        <itemtemplate>
                            <asp:Label ID="Label1" runat="server" Text='<%# format_name(Convert.ToString(Eval("LastName")), Convert.ToString(Eval("FirstNameMI"))) %>'></asp:Label>
                        </itemtemplate>
                    </asp:templatefield>
                    <asp:boundfield DataField="EditDate" HeaderText="Last Updated"
                        SortExpression="EditDate">
                    </asp:boundfield>
                </Columns>
            </asp:GridView>


 

I think you need to do something like this

HyperLink hl = (HyperLink)e.Row.FindControl("nameofhyperlink");

hl.NavigateUrl +=  "&missing_info=account";

 Thanks ghinx!

 I ended up converting that column to a HyperLinkField and was then able to go straight to the controls collection like:

((HyperLink)e.Row.Cells[1].Controls[0]).NavigateUrl += "&missing_info=account";

I did verify that your suggestion did work, though.