I have a webform with a username, password and user identifier that classifies a user as an "A" for admin or "U" for standard user.When you submit the form it should write to the database I have setup in visual studio, which currently already has other users.When I test the web form I get an error "NullReferenceException was unhandled by user code", "Object reference not set to an instance of an object." and it points to this line of code on my web form page.\[code\]clsDataLayer.SaveUser(Server.MapPath("PayrollSystem_DB.mdb"), Session["txtUserName"].ToString(), Session["txtPassword"].ToString(), Session["drpdwnlstSecurityLevel"].ToString());\[/code\]Do you see anything wrong with this line of code? I have a textbox labeled "txtPassword", a textbox labeled "txtPassword" and a dropdown list with the option of U or A labeled "drpdwnlstSecurityLevel".When you submit the information it is supposed to send it to my clsDataLayer.cs SaveUser method which is:\[code\]public static bool SaveUser(string Database, string UserName, string UserPassword, string SecurityLevel) { bool userSaved; try { // Define SQLConnClass OleDbConnection conn = new OleDbConnection("PROVIDER=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + Database); conn.Open(); OleDbCommand command = conn.CreateCommand(); string strSQL; // this insert data to user table strSQL = "Insert into tblUserLogin " + "(UserName, UserPassword, SecurityLevel) values ('" + UserName + "', '" + UserPassword + "', " + SecurityLevel + "')"; // this gives a command to get or set values command.CommandType = CommandType.Text; command.CommandText = strSQL; // This sql statements brings out the affacted rows command.ExecuteNonQuery(); // closes the connection conn.Close(); userSaved = true; } catch (Exception ex) { userSaved = false; } return userSaved; }\[/code\]When you try to create a new user with my webform it does not create any record, it only issues the error I mentioned.Here is all of my code that is relative to this question:FILE clsDataLayer.cs:// This function saves the user datapublic static bool SaveUser(string Database, string UserName, string UserPassword, string SecurityLevel){\[code\]bool userSaved;try{ // Define SQLConnClass OleDbConnection conn = new OleDbConnection("PROVIDER=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + Database); conn.Open(); OleDbCommand command = conn.CreateCommand(); string strSQL; // this insert data to user table strSQL = "Insert into tblUserLogin " + "(UserName, UserPassword, SecurityLevel) values ('" + UserName + "', '" + UserPassword + "', " + SecurityLevel + "')"; // this gives a command to get or set values command.CommandType = CommandType.Text; command.CommandText = strSQL; // This sql statements brings out the affacted rows command.ExecuteNonQuery(); // closes the connection conn.Close(); userSaved = true;}catch (Exception ex){ userSaved = false;}return userSaved;\[/code\]}FILE frmManageUsers.aspx.cs:\[code\]using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;public partial class frmManageUsers : System.Web.UI.Page{ protected void Page_Load(object sender, EventArgs e) { } protected void btnAddUser_Click(object sender, EventArgs e) { string userName, userPassword; if (txtUserName.Text == "" || txtUserName.Text == null) { lblUserError.Text = ("User Name may not be empty"); lblUserError.ForeColor = System.Drawing.Color.Red; return; } else userName = (txtUserName.Text); if (txtPassword.Text == "" || txtPassword.Text == null) { lblUserError.Text = ("Password may not be empty"); lblUserError.ForeColor = System.Drawing.Color.Red; return; } else { userPassword = (txtPassword.Text); } // clsDataLayer.SaveUser(Server.MapPath("PayrollSystem_DB.mdb"), Session["txtUserName"].ToString(), Session["txtPassword"].ToString(), Session["drpdwnlstSecurityLevel"].ToString()); clsDataLayer.SaveUser( Server.MapPath("PayrollSystem_DB.mdb"), txtUserName.Text, txtPassword.Text, drpdwnlstSecurityLevel.SelectedValue ); Server.Transfer("frmManageUsers.aspx"); }}\[/code\]FILE frmManageUsers.aspx:\[code\]<%@ Page Language="C#" AutoEventWireup="true" CodeFile="frmManageUsers.aspx.cs" Inherits="frmManageUsers" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head id="Head1" runat="server"> <title></title></head><body> <form id="form1" runat="server"> <div align="center"> <a href="http://stackoverflow.com/questions/13751908/frmMain.aspx"> <font color="black" size="2" style="text-align: center"><strong> <font color="blue" face="Comic Sans MS" size="4">Cool</font> <font color="#ff6600" face="Comic Sans MS" size="4">Biz</font> <font face="Comic Sans MS" size="4"> <font color="#993366">Productions</font>, Inc.</font></strong></font> </a> <br /> <br /> <asp:Label ID="Label1" runat="server" Text="Manage Users"></asp:Label> <br /> <asp:Label ID="Label2" runat="server" Text="User Name: "></asp:Label> <asp:TextBox ID="txtUserName" runat="server"></asp:TextBox> <br /> <asp:Label ID="Label3" runat="server" Text="Password: "></asp:Label> <asp:TextBox ID="txtPassword" runat="server"></asp:TextBox> <br /> <asp:Label ID="lblUserError" runat="server"></asp:Label> <br /> <asp:Label ID="Label4" runat="server" Text="Security Level: "></asp:Label> <asp
ropDownList ID="drpdwnlstSecurityLevel" runat="server" DataSourceID="SqlDataSource2" DataTextField="SecurityLevel" DataValueField="SecurityLevel"> <asp:ListItem></asp:ListItem> <asp:ListItem></asp:ListItem> </aspropDownList> <asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings
ayrollSystem_DBConnectionString %>" ProviderName="<%$ ConnectionStringsayrollSystem_DBConnectionString.ProviderName %>" SelectCommand="SELECT [SecurityLevel] FROM [tblUserLogin]"> </asp:SqlDataSource> <br /> <br /> <asp:Button ID="btnAddUser" runat="server" onclick="btnAddUser_Click" Text="Add User" /> <br /> <br /> <asp:GridView ID="grdUserLogin" runat="server" AutoGenerateColumns="False" DataSourceID="SqlDataSource1"> <Columns> <asp:BoundField DataField="UserID" HeaderText="UserID" InsertVisible="False" SortExpression="UserID" /> <asp:BoundField DataField="UserName" HeaderText="UserName" SortExpression="UserName" /> <asp:BoundField DataField="UserPassword" HeaderText="UserPassword" SortExpression="UserPassword" /> <asp:BoundField DataField="SecurityLevel" HeaderText="SecurityLevel" SortExpression="SecurityLevel" /> </Columns> </asp:GridView> <br /> <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStringsayrollSystem_DBConnectionString %>" InsertCommand="INSERT INTO [tblUserLogin] ([UserID], [UserName], [UserPassword], [SecurityLevel]) VALUES (?, ?, ?, ?)" ProviderName="<%$ ConnectionStringsayrollSystem_DBConnectionString.ProviderName %>" SelectCommand="SELECT * FROM [tblUserLogin]"> <InsertParameters> <asparameter Name="UserID" Type="Int32" /> <asparameter Name="UserName" Type="String" /> <asparameter Name="UserPassword" Type="String" /> <asparameter Name="SecurityLevel" Type="String" /> </InsertParameters> </asp:SqlDataSource> </div> </form></body></html>\[/code\]
ropDownList ID="drpdwnlstSecurityLevel" runat="server" DataSourceID="SqlDataSource2" DataTextField="SecurityLevel" DataValueField="SecurityLevel"> <asp:ListItem></asp:ListItem> <asp:ListItem></asp:ListItem> </aspropDownList> <asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStringsayrollSystem_DBConnectionString %>" ProviderName="<%$ ConnectionStringsayrollSystem_DBConnectionString.ProviderName %>" SelectCommand="SELECT [SecurityLevel] FROM [tblUserLogin]"> </asp:SqlDataSource> <br /> <br /> <asp:Button ID="btnAddUser" runat="server" onclick="btnAddUser_Click" Text="Add User" /> <br /> <br /> <asp:GridView ID="grdUserLogin" runat="server" AutoGenerateColumns="False" DataSourceID="SqlDataSource1"> <Columns> <asp:BoundField DataField="UserID" HeaderText="UserID" InsertVisible="False" SortExpression="UserID" /> <asp:BoundField DataField="UserName" HeaderText="UserName" SortExpression="UserName" /> <asp:BoundField DataField="UserPassword" HeaderText="UserPassword" SortExpression="UserPassword" /> <asp:BoundField DataField="SecurityLevel" HeaderText="SecurityLevel" SortExpression="SecurityLevel" /> </Columns> </asp:GridView> <br /> <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStringsayrollSystem_DBConnectionString %>" InsertCommand="INSERT INTO [tblUserLogin] ([UserID], [UserName], [UserPassword], [SecurityLevel]) VALUES (?, ?, ?, ?)" ProviderName="<%$ ConnectionStringsayrollSystem_DBConnectionString.ProviderName %>" SelectCommand="SELECT * FROM [tblUserLogin]"> <InsertParameters> <asparameter Name="UserID" Type="Int32" /> <asparameter Name="UserName" Type="String" /> <asparameter Name="UserPassword" Type="String" /> <asparameter Name="SecurityLevel" Type="String" /> </InsertParameters> </asp:SqlDataSource> </div> </form></body></html>\[/code\]