adding user to a role when registering

Question

I am using the built-in register module in asp.net application for registering new users. I am trying to set the role for the user when they are registering but for some reason I can't access the textbox control in the backend code to add the new user to the selected role, I am trying to find the textbox with this code too, but it returns null, meaning that the control can't be found:

 TextBox txtUsername = (TextBox)Page.FindControl("UserName");
            Roles.AddUserToRole(txtUsername.Text, "User");  

Also, here is the html markup for the register module:

   <asp:CreateUserWizardStep ID="RegisterUserWizardStep" runat="server">
                <ContentTemplate>
                    <h2>
                        Create a New Account
                    </h2>
                    <p>
                        Use the form below to create a new account.
                    </p>
                    <p>
                        Passwords are required to be a minimum of <%= Membership.MinRequiredPasswordLength %> characters in length.
                    </p>
                    <span class="failureNotification">
                        <asp:Literal ID="ErrorMessage" runat="server"></asp:Literal>
                    </span>
                    <asp:ValidationSummary ID="RegisterUserValidationSummary" runat="server" CssClass="failureNotification" 
                         ValidationGroup="RegisterUserValidationGroup"/>
                    <div class="accountInfo">
                        <fieldset class="register">
                            <legend>Account Information</legend>
                            <p>
                                <asp:Label ID="UserNameLabel" runat="server" AssociatedControlID="UserName">User Name:</asp:Label>
                                <asp:TextBox ID="UserName" runat="server" CssClass="textEntry"></asp:TextBox>
                                <asp:RequiredFieldValidator ID="UserNameRequired" runat="server" ControlToValidate="UserName" 
                                     CssClass="failureNotification" ErrorMessage="User Name is required." ToolTip="User Name is required." 
                                     ValidationGroup="RegisterUserValidationGroup">*</asp:RequiredFieldValidator>
                            </p>
                            <p>
                                <asp:Label ID="EmailLabel" runat="server" AssociatedControlID="Email">E-mail:</asp:Label>
                                <asp:TextBox ID="Email" runat="server" CssClass="textEntry"></asp:TextBox>
                                <asp:RequiredFieldValidator ID="EmailRequired" runat="server" ControlToValidate="Email" 
                                     CssClass="failureNotification" ErrorMessage="E-mail is required." ToolTip="E-mail is required." 
                                     ValidationGroup="RegisterUserValidationGroup">*</asp:RequiredFieldValidator>
                            </p>
                            <p>
                                <asp:Label ID="PasswordLabel" runat="server" AssociatedControlID="Password">Password:</asp:Label>
                                <asp:TextBox ID="Password" runat="server" CssClass="passwordEntry" TextMode="Password"></asp:TextBox>
                                <asp:RequiredFieldValidator ID="PasswordRequired" runat="server" ControlToValidate="Password" 
                                     CssClass="failureNotification" ErrorMessage="Password is required." ToolTip="Password is required." 
                                     ValidationGroup="RegisterUserValidationGroup">*</asp:RequiredFieldValidator>
                            </p>
                            <p>
                                <asp:Label ID="ConfirmPasswordLabel" runat="server" AssociatedControlID="ConfirmPassword">Confirm Password:</asp:Label>
                                <asp:TextBox ID="ConfirmPassword" runat="server" CssClass="passwordEntry" TextMode="Password"></asp:TextBox>
                                <asp:RequiredFieldValidator ControlToValidate="ConfirmPassword" CssClass="failureNotification" Display="Dynamic" 
                                     ErrorMessage="Confirm Password is required." ID="ConfirmPasswordRequired" runat="server" 
                                     ToolTip="Confirm Password is required." ValidationGroup="RegisterUserValidationGroup">*</asp:RequiredFieldValidator>
                                <asp:CompareValidator ID="PasswordCompare" runat="server" ControlToCompare="Password" ControlToValidate="ConfirmPassword" 
                                     CssClass="failureNotification" Display="Dynamic" ErrorMessage="The Password and Confirmation Password must match."
                                     ValidationGroup="RegisterUserValidationGroup">*</asp:CompareValidator>
                            </p>
                        </fieldset>
                        <p class="submitButton">
                            <asp:Button ID="CreateUserButton" runat="server" CommandName="MoveNext" Text="Create User" 
                                 ValidationGroup="RegisterUserValidationGroup"/>
                        </p>
                    </div>
                </ContentTemplate>
                <CustomNavigationTemplate>
                </CustomNavigationTemplate>
            </asp:CreateUserWizardStep>

Any idea what am I doing wrong? Thanks, Laziale

Answer 1

That's because your UserName text box is not a direct child of the page. It is nested within many controls. Here's how, recursively, you can search through all the controls in your page to get an instance of your UserName text box:

private TextBox getUserNameTextBox(ControlCollection ctls)
    {
        foreach (Control c in ctls)
        {
            if (c is System.Web.UI.WebControls.TextBox)
            {
                if (c.ID == "UserName")
                    return c;
            }
            if (c.HasControls())
            {
                getAllCtl(c.Controls);


            }
        }
        return null;
    }

YourUserNameTextBox = getuserNameTextBox(Page.Controls);