Web Forms :: Master Page Controls Cause Null Reference Exceptions?
Mar 10, 2010
I've got a master page where I've created two content place holders ('menu content place holder' and 'main body content place holder'). I've placed several controls (drop down lists and a calendar) in one of these content place holders (the 'menu content place holder'). In my content page I've set the 'menu content place holder' to 'Default to Master page content'. In my 'main body content place holder' I've included several controls (table, labels) which depend on the user selected items in the 'menu content place holder'.
After including a reference in all the necessary places- like this:
DropDownList ddlList1 = Master.FindControl("ddlList1")
as
DropDownList;
I still get the following exception (this exception occurs in my content page):
An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details:System.NullReferenceException: Object reference not set to an instance of an object.
Source Error:
[Code]....
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Sep 30, 2010
in my default.aspx page i have a dropdown List and a textbox with a submit button below that there are 2 listbox... and the dropdown list holds the names of the listbox
my logic here is to select an item from the dropdown list and put some text in the text box and submit the form which will add an item to the listbox selected.. but when i do this i get an error saying Object reference not set to an instance of an object. i tried to figure out the problem and found that when i remove the reference to the Site Master Page it works fine and when i undo and apply my reference back to the Site Master Page i get the same error.
[Code]....
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Nov 18, 2010
I have a user control with GridView. GridView template has label that suppose to get custom object value Name.
aspx:
<asp:Label ID="lblImage" runat="server" Text='<%# MyData.Name%>' />
cs:
public MyObject MyData;
During page loading MyData object is null, so I'm getting exception: "Object reference not set to an instance of an object.".
How to avoid the error?
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Aug 20, 2010
I developed a page in VWD 2008 and it works perfectly locally, but when I deployed it on the server every Page.FindControl() call is causing the NullReference Exception "Object reference not set to an instance of an object. " Can anyone help me out? Code is below
[Code]....
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Aug 5, 2010
I am attempting to access a textbox control on a master page from a code behind base class but having problems.
I have 3 levels of master pages. m1.master is the master page for m2.master which is the master page for m3.master.
m3.master has a textbox as shown below
<%Master
Language="C#"
MasterPageFile="~/m2.master"
AutoEventWireup="true"
CodeFile="M3.master.cs"
Inherits="M3"
%>
<asp:Content
ID="Content5"
ContentPlaceHolderID="M2"
Runat="Server">
<asp:TextBox
ID="text1"
runat="server"
></asp:TextBox>
<asp:ContentPlaceHolder
ID="M3"
runat="Server"></asp:ContentPlaceHolder>
</asp:Content>
I have a content page c1.aspx that uses m3.master as its master page as shown below:
<%@
Page
Title=""
Language="C#"
MasterPageFile="~/m3.master"
AutoEventWireup="true"
CodeFile="c1.aspx.cs"
Inherits="_c1"
%>
<%@
MasterType
VirtualPath="~/m3.master"
%>
<asp:Content
ID="Content1"
ContentPlaceHolderID="M3"
Runat="Server">
</asp:Content>
My content page codebehind class inherits from a base class BaseForm
public partial
class
_c :
BaseForm{}
The problem that i am having is that I cannot access the texbox from the class BaseForm. The BaseForm code is as follows:
using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public...........
I'm getting a null reference exception for txt1
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Feb 15, 2011
my MasterPage I have a label that reflects the name of the module that the user is currently in. I change the label text accordingly using the following ..
private void ChangePageTitle(string PageTitle)
{
Label lblPageTitle = (Label)Master.FindControl("lblPageTitle");
lblPageTitle.Text = PageTitle;
}
Instead of placing this method in the code-behind of every page, I want to put it in a single class and call it accordingly. I thought of using a static class but do not know how to reference the MasterPage.Can I use a static class? or do I place the method in the code-behind of one page and call Object.Method from the other pages?
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Aug 8, 2010
I am attempting to access a textbox control on a master page from a code behind base class but having problems. I have 3 levels of master pages. m1.master is the master page for m2.master which is the master page for m3.master.m3.master has a textbox as shown below
<%Master
Language="C#"
MasterPageFile="~/m2.master"
AutoEventWireup="true"
CodeFile="M3.master.cs"
Inherits="M3"
%>
<asp:Content
ID="Content5"
ContentPlaceHolderID="M2"
Runat="Server">
<asp:TextBox
ID="text1"
runat="server"
></asp:TextBox>
<asp:ContentPlaceHolder
ID="M3"
runat="Server"></asp:ContentPlaceHolder>
</asp:Content>
I have a content page c1.aspx that uses m3.master as its master page as shown below:
@
Page
Title=""
Language="C#"
MasterPageFile="~/m3.master"
AutoEventWireup="true"
CodeFile="c1.aspx.cs"
Inherits="_c1".................
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Jul 10, 2010
I have created a masterpage where I require user login. The content pages are only displayed if the user is authenticated.
<LoggedInTemplate>
<asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
</asp:ContentPlaceHolder>
</LoggedInTemplate>
On my content page I have
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<asp:DropDownList ID="dropdown1" runat="server"></asp:DropDownList>
</asp:Content>
When run, I can successfully authenticate and then when I attempt to view this particular content page I get an error on the page load where I'm trying to populate the dropdownlist. The error I get is a Null Reference exception. I don't fully understand the page lifecycle of an asp.net page, but I also don't understand why the page compiles successfully and its only when run that I get this exception. It seems that the control is not created when the page_load command is called. How can I change the contents of a dropdownlist on page load of a content page that requires authentication?
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Mar 1, 2010
Here is my simple class, where i inherit from UserControl.
public class Test:System.Web.UI.UserControl
{
public void BindGrid()
[code]...
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Nov 2, 2010
So I have followed this tutorial to try and me edit a record in a datalist.
[URL]
When I click update after updating anyfield it throws a NullReferenceException was unhandled by the user code. Here is my code.
protected void DataList1_UpdateCommand(object source,
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Sep 2, 2010
Null Reference Exception was not handled by user Object Reference not set to instance of an object
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Mar 23, 2010
Why would i be getting NullReferenceException if im setting the labels with values?In my page_load i have the following:
Label hireMess = (Label)FormView1.FindControl("hireMess");
Label hireEnd = (Label)FormView1.FindControl("hireEnd");
HyperLink hyptry = (HyperLink)FormView1.FindControl("hyptry");
and right below that i have 1 condition to check for and then set the Text value of the 2 labels.hireMess.Text = "It Was Successfully!";hireEnd.Text ="You will be re-directed to your Pool in 10 seconds.";I compared the page to production and eveyrthing is the same and production doesnt have any issues.. not sure why its coming up null.The error comes up for the first label:Object reference not set to an instance of an object. Description:An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.Source Error:
[Code]....
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May 19, 2010
i have null reference exception in grid view, in the
string s = ((Label)GridView1.FindControl("Label6")).Text;
i tryed this to e.Values["EventId"].ToString()
but still the some why is that?
the full code :
[Code]....
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Feb 16, 2010
I have a class that derives from System.Web.UI.Page and have set my pages to derive from this custom page class instead of Page. At runtime, the controls are never initialized and throw a NullReferenceException. I've changed some class names and namespaces in the pasted code to protect the innocent. The only thing that I currently override in my PageBase is OnPreLoad and I do call the base.OnPreLoad. I'll eventually add more functionality to this PageBase but for now all that it has is this:
[Code]....
I've tried putting this into a class library (with System.Web referenced) and I've also tried moving the class into the web application and had the same results either way. As another strange twist, I have another class with derives from PageBase called IndexPageBase and it doesn't have this problem:
[Code]....
[Code]....
[Code]....
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Nov 2, 2010
I am using Asp.Net C# 2.0. My website is working fine in local. Website contains 2 js files included in master page. It works fine in local environment, but when i publish my website i get "Object expected" error on page load, and thus the js functions are not working in published website.
Currently i am writing <script src="/javascripts/jquery.hotkeys-0.7.9.js" type="text/javascript"></script> in master page.
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Feb 24, 2010
I am using dropdownlist in my view page with some values which will display corresponding ID(primary key of other table) in my database.If i leave my dropdownlist blank and save it in database then its showing null parameter error. Can you explain how to use this reference type to overcome this error
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Apr 6, 2010
Have created a Webform based on a master page.The code executes OK and sends data to the database, but inserts null values for all entries except the GetDate.
If I use exactly the same code in a new webform which isn't based on the master page, it inserts everything correctly.Here is a snippet from the form which uses the master page: -
<%@ Page Title="" Language="C#" MasterPageFile="~/SpeedDateMasterPage.master" %>
<script runat="server">
private void AddToDatabase(object source, EventArgs e) [code].....
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Jun 10, 2010
Im trying to use code provide in this link below.http://www.codeproject.com/KB/aspnet/MultipleTabWindows.aspxim trying to have the below code in my master page instead of adding to each page. it works if i add to each page, but when i add to ,master page the session value for "WindowName" is always null.how can i fix this?
<script language="javascript" type="text/javascript">if(window.name != "<%=GetWindowName()%>"){ window.name = "invalidAccess"; window.open("InvalidAccess.aspx", "_self");}</script>public string GetWindowName(){ return Session["WindowName"].ToString();}
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Jan 14, 2010
I have a gridview,when i do it is giving me null object reference error.
I am posting my code for your reference -
[Code]....
My gridview code is -
[Code]....
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Feb 15, 2011
My Original Issue here:Help! I've got repository access in my MVC master page! Refactor time!What originated as a re factoring job to improve performance has revealed new issues. If I should keep this in my original question - feel free to delete this one, and rename the old one to something more relevant. I'm using an ActionFilter applied to a base controller to load some user-customized settings. My issue is that I save these settings in the filterContext.Controller.ViewData object but its coming through as null on my master page. Here is the relevant code:
Action Filter
[AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
public class StoreSettingsActionFilter : ActionFilterAttribute
[code]...
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Mar 6, 2010
I'm new to programming in ASP.NET, but I'm making my way through Wrox's Beginning ASP.NET 3.5 in C# and VB.NET.
I'm at a section where I'm creating a BasePage. I successfully created a BasePage by creating a new class file in my App_Code folder called BasePage.cs with the following code:
[Code]....
If I run that code everything works out fine. The page loads and all is well. But, if I try to do the same thing to a page that uses my MasterPage.master file, I get the following error:
Object reference not set to an instance of an object.
Description:
An unhandled exception occurred during the execution of the current web request. review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
Why is that? In the example code from the book (that also uses a MasterPage.master file), everything excutes and runs just fine. But in my test, I get the above error. I've tried comparing my pages to the books included source pages, but I can't find any differences.
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Aug 31, 2010
i have create dynamic menu control , i have master page and login page , once the user login , i want to show the dynamic menu in my master page. below i try to call masterpage control in my child page ,but i throughs the error
Object reference not set to an instance of an object.
my master page code
public partial class MasterPage : System.Web.UI.MasterPage
{
protected void Page_Load(object sender, EventArgs e)
{
}
public string MyProperty
{
set
{
// lblUser.Text = value;
lblUser.Text = value; // here i got the error
}
}
}
My child page code
protected void btnwork_Click(object sender, EventArgs e)
{
((MasterPage)this.Master).MyProperty = "Text changed from Sub Page";
}
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Apr 30, 2010
Object reference not set to an instance of an object.
iam getting this Error Just created the controls as an null and how to create the object for reference
1) as my analysis i got the information that i need to create the object reference with new keyword but how to do it script using c#
public TextBox txtEventDate = null;
public Calendar calEventDate = null;
public Label lblResult = null;
protected void calEventDate_SelectionChanged (Object sender,EventArgs e)
{
this.txtEventDate = this.FindControl("txtEventDate") as TextBox;
this.calEventDate = this.FindControl("calEventDate") as Calendar;
txtEventDate.Text = calEventDate.SelectedDate.ToString ("d");
}
protected void btnSubmit_Click(Object Sender,EventArgs e)
{
this.lblResult = this.FindControl("lblResult") as Label;
lblResult.Text = "You Picked" + txtEventDate.Text;
}
</script>
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Jan 26, 2010
I'm building the standard 3-tier ASP.NET web application but I'm struggling as to where to do certain things - specifically handling exceptions.
I've tried to have a look around on the web for some examples but can't find any which go as far as a whole project showing how everything links together.
In my data-tier I'm connecting to SQL Server and doing some stuff. I know I need to catch exceptions that could be raised as a result but I'm not sure where to do it.
From what I've read I should be doing it in the UI tier but in that case I'm not sure how to ensure that the connection to the database is closed. Is anyone able to clarify how to do this? Also if anyone knows as to where I could find an example 3-tier web application that follows best practices that would be great too.
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Sep 10, 2010
xamount is receiving this message on the last line. The session is being set in the previous page. Is there a way to resolve the message or should I just use a previous page postback
[Code]....
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