Adding Form Validation to ADFS Login

I need to add a check for form variables that are passed to my adfs login page but when I add anything to the built-in Page_Load function it breaks.

FormsSignIn.aspx

<%@ Page Language="C#" MasterPageFile="~/MasterPages/MasterPage.master" AutoEventWireup="true"  ValidateRequest="false"
    CodeFile="FormsSignIn.aspx.cs" Inherits="FormsSignIn" Title="<%$ Resources:CommonResources, FormsSignInPageTitle%>"
    EnableViewState="false" runat="server"%>
<%@开发者_如何学Python OutputCache Location="None" %>

<asp:Content ID="FormsSignInContent" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
    <div class="GroupXLargeMargin"><asp:Label Text="<%$ Resources:CommonResources, FormsSignInHeader%>" runat="server" /></div>
    <h3>*******I Want lbl1.Text to output here from the codefile.</h3>
    <table class="UsernamePasswordTable">
        <tr>
            <td>
                <span class="Label"><asp:Label Text="<%$ Resources:CommonResources, UsernameLabel%>" runat="server" /></span>
            </td>
            <td>
                <asp:TextBox runat="server" ID="UsernameTextBox" ></asp:TextBox>            
            </td>
            <td class="TextColorSecondary TextSizeSmall">
                <asp:Label Text="<%$ Resources:CommonResources, UsernameExample%>" runat="server" />
            </td>
        </tr>
        <tr>
            <td>
                <span class="Label"><asp:Label Text="<%$ Resources:CommonResources, PasswordLabel%>" runat="server" /></span>
            </td>
            <td>
                <asp:TextBox runat="server" ID="PasswordTextBox" TextMode="Password" ></asp:TextBox>            
            </td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td></td>
            <td colspan="2" class="TextSizeSmall TextColorError">
                <asp:Label ID="ErrorTextLabel" runat="server" Text="" Visible="False"></asp:Label>
            </td>
        </tr>
        <tr>
            <td colspan="2">
                <div class="RightAlign GroupXLargeMargin">
                    <asp:Button ID="SubmitButton" runat="server" Text="<%$ Resources:CommonResources, FormsSignInButtonText%>" OnClick="SubmitButton_Click" CssClass="Resizable"/>
                </div>
            </td>
            <td>&nbsp;</td>
        </tr>
    </table>
</asp:Content>

FormsSignIn.Aspx.cs

using System;
using Microsoft.IdentityServer.Web;
using Microsoft.IdentityServer.Web.UI;

public partial class FormsSignIn : FormsLoginPage
{
    protected void Page_Load( object sender, EventArgs e )
    {
            //Uncommented, this breaks!!!!!!!!!!!!!!
        /* if ( !string.IsNullOrEmpty(Page.Request.Form["foo"]) ) {
                lbl1.Text = Page.Request.Form["foo"].Trim();
        } else {
                lbl1.Text = "not found";
            } */
    }

    protected void HandleError( string message )
    {
        ErrorTextLabel.Visible = true;
        ErrorTextLabel.Text = Resources.CommonResources.IncorrectUsernameText;
    }

    protected void SubmitButton_Click( object sender, EventArgs e )
    {
        try
        {
            SignIn( UsernameTextBox.Text, PasswordTextBox.Text );
        }
        catch ( AuthenticationFailedException ex )
        {
            HandleError( ex.Message );
        }
    }
}

You haven't mentioned how you added the code or how it breaks but, in general, I have found problems when I modify the files directly.

Given that ADFS is just another IIS application, I have more joy following this approach:

Modifying and Securing the ADFS 2 Web Application