Web Forms :: How To Prevent Nullreference Exception
Dec 9, 2010How do I prevent nullreference exception (Object reference not set to an instance of an object.) on
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specifically on referencing ClientID of the control in JavaScript
Similar Messages:
Web Forms :: NullReference Exception Unhandled By User Code?
Mar 18, 2011I'm working on having two forms that communicate together. In order to do this, I am passing public value from the source page. Here's how I did it:
In the source page I have:
Public ReadOnly Property CurrentCity() As String
Get
Return txtboxfake.Text
End Get
End Property
Then under page_load of the page I have:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
txtteam.Text = PreviousPage.CurrentCity
txtboxdate.Text = Calendar1.SelectedDate
End Sub
For some reason I keep getting an error that says "NullReference exception unhandled by user code" that points to txtteam.text = PreviousPage.CurrentCity.
C# - Keep Getting Nullreference Exception
Nov 19, 2010Panel pnl_Confirmation = (Panel)form1.FindControl("ConfirmationPanel") as Panel;
pnl_Confirmation.Visible = false;
I keep getting a "NullReferenceException" in the above code. "ConfirmationPanel" is a panel I show/hide depending on if the form is submitted successfully or not.
The panel is wrapped in a LoginView control, which is why I cannot call "ConfirmationPanel" directly:
<asp:LoginView ID="LoginView1" runat="server">
<LoggedInTemplate>
<asp:Panel id="ConfirmationPanel" runat="server" Wrap="False">
...
Why is this null? It should be referencing the Panel with the ID "ConfirmationPanel", no?
Getting NullReference Exception In C#?
Jan 19, 2011The following is a web method that is called from ajax, I have verified with firebug that the script is indeed passing two string values to my method:
public string DealerLogin_Click(string name, string pass)
{
string g="adf";
if (name == "w" && pass == "w")
{
HttpContext.Current.Session["public"] = "pub";
g= "window.location = '/secure/Default.aspx'";
}
return g;
}
I'm passing "w" just for testing purposes. If I delete the if block then I don't get an error back from the server. I'm confused.
Forms Data Controls :: DetailsView System.NullReference Exception Error
Jan 25, 2011Im having issues with a webform that previously worked before I added a dropdownlist.selectedindexchanged event related to the data that the details view displayed. I ran it in debugging mode and the variable has a valid value. Heres the line Im getting
the error on:
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Security - Prevent Web Caching Throwing Exception?
Jan 18, 2011I am trying to stop the caching of web pages using the following snippets in the ASP.NET however its not working and showing following error to me,
Response.CacheControl = "no-store";
Response.AddHeader("Pragma", "no-cache");
Response.Expires = -1;
[code]...
Empty Catch In Global.asax To Prevent Exception From Stopping A Web Application?
Sep 28, 2010I'm using a static Timer in my Global.asax to run a method at regular intervals. When the method throws an exception, my application is stopped. I have used an empty catch to prevent exceptions from stopping the application something like below code. Is there a disadvantage to use such an approach?
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Web Forms :: NullReference Error / Running Windows Service
Mar 29, 2011Hello all. I created a class that runs fine when using it with web forms, however when i create a Windows service and try to run it I recieve a NullReference error. Im not sure what else to do since the class works fine.Here is a snippet.
The service
public partial class Service1 : ServiceBase
{
//Timer object
Timer RunTime;
QBridge bridge_object = new QBridge()
double test_interval = 40000; //test value
public Service1()
{
InitializeComponent();
}
protected override void OnStart(string[] args)
{
//Send email notification that intakes were pushed
//bridge_object.SendNotification(bridge_object.service_startedtext);
RunTime = new Timer(30000);
//set the elapsed event
RunTime.Elapsed += new ElapsedEventHandler(RunTime_Elapsed);
//RunTime.Interval = SetInterval(); //calculated interval
RunTime.Interval = test_interval; // test interval
RunTime.Enbled = true; //set timer to true
//QBridge bridge_object = new QBridge();
//bridge_object.SendNotification("start");
//SendNotification("start");
}
protected override void OnStop()
{
RunTime.Enabled = false; RunTime.Dispose();
try
{
bridge_object.SendNotification("stop");
}
catch (NullReferenceException nre) { System.Windows.Forms.MessageBox.Show("Error " + nre); }
catch (Exception er) { System.Windows.Forms.MessageBox.Show("Error " + er); }
//SendNotification("end");
}
//Included this to test locally. works fine when just calling the method
protected void RunTime_Elapsed(object source, ElapsedEventArgs e)
{
//SendNotification("run");
try
{
bridge_object.SendNotification(run);
}
catch (NullReferenceException nre) { System.Windows.Forms.MessageBox.Show("Error " + nre); }
catch (Exception er) { System.Windows.Forms.MessageBox.Show("Error " + er); }
}
public void SendNotification(string email_text)
{
MailMessage initial = new MailMessage();
initial.Bcc.Add(new MailAddress(""));
initial.From = new MailAddress("");
initial.Subject = "Web notification";
initial.IsBodyHtml = true;
initial.Body = email_text;
SmtpClient mailClient = new SmtpClient("192.168.1.1");
try
{
mailClient.Send(initial);
}
catch (Exception ex) { }
}
}
Class
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Net.Mail;
using System.IO;
using System.Configuration;
using System.Data.SqlClient;
using System.Data;
namespace Intake
{
public class QBridge
{
SqlConnection con =
new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
private string login_error;
public QBridge()
{
}
public void SendNotification(string email_text)
{
MailMessage initial = new MailMessage();
initial.Bcc.Add(new MailAddress(""));
initial.From = new MailAddress("");
initial.Subject = "Web notification";
initial.IsBodyHtml = true;
initial.Body = email_text;
SmtpClient mailClient = new SmtpClient("192.168.1.1");
try
{
mailClient.Send(initial);
}
catch (Exception ex) { }
}
}
}
DataSource Controls :: Getting Exception / An Exception Occurred While Executing A Transact-SQL Statement Or Batch
Jan 1, 2010i need to restore Database.mdf; I create a blank new database exactly the same name as the .mdf file. However, I could not restore the database.
The error message prompted was:
TITLE: Microsoft SQL Server Management Studio Express
An exception occurred while executing a Transact-SQL statement or batch.
(Microsoft.SqlServer.Express.ConnectionInfo)
ADDITIONAL INFORMATION:
Cannot open backup device 'C:inetpubwwwrootTCPSystemApp_DataDatabase.mdf'. Operating system error 32(error not found).
RESTORE HEADERONLY is terminating abnormally. (Microsoft SQL Server, Error: 3201)
click: [URL]
BUTTONS:
OK
Architecture :: How To Log Dal Exception And Showing Alert To User / Exception Occurs
Aug 3, 2010I am working on a 3-tier asp.net application. Currently I'm stuck up in a situation where I need to handle a specific type of exception (User Defined) in DAL and Show alert to the user if that exception occurs in DAL.
I tried following things:
1) I raised that exception from the DAL and catch it in BLL and throw a new BLL exception to for that DAL exception and finally catch it in the UI layer to show the alert to the user. I've successfully implement this in my project. But there are some issues in this approach. First of all I feel this is not right way to do this as it may lead to performance related issues. Secondly, the application contains more than 500 pages and classes. so I need to attach additional catch block in every method to catch the BLL exception. which is the last option i'd like to take.
2) in second approach I logged the the DAL exception into a text file. but problem in this approach is that how could the UI layer know that exception has occurred and show the alert to the user. Is there any event in asp.net where i could handle all this activities?
my question is what is the best approach to handle this type of situation? Will Exception handling block help me in this?
I've tried reading many articles on this but i couldn't get an answer for my question? I might not be using right keywords for my search.
C# - How Do I Get Specific Details About An Exception From A General Exception Class Object
Feb 4, 2010In ASP.NET,How can i know the Specific details about an exception (like What kind of Exception it is (FileNotFound /Arithmentc etc..) )from a General Exception class object.
View 2 RepliesC# - Exception Handling - Implement Custom Exception Classes?
Jul 2, 2010i have this application structure:
1. Presentation Layer which calls
2. Business Logic Layer which in turn calls
3. Data Access Layer to do the dealing with the database.
Now i have a Contacts page from where i can add a new contact to the database.So to add a New Contact i fill in all the required details and then call a Add Method (residing in the BLL) from the page, which in turn call a Add Method residing in the DAL.this method in the DAL returns the Current Identity of the record which is then return back to the BLL method and finally delivered on the page.this is fine. but what if a get an exception how do i handle it properly because the method in DAL has a return type of int and i dont want to throw another error!! coz other wise i will have to write try catch in almost all the methods.
//something like this
public int AddMethod(ContactClass contactObj)
{
int result = 0;[code]...
rather i want to show the user a user-friendly message which they can easily understand and in the mean while i will send a mail to myself documenting the Error that just occurred.how can i implement my custom exception classes.
Ways To Identify A Particular Exception From Exception Class?
May 18, 2010Is there any way to uniquely identify a particular exception from the general exception class.
i.e any property or method that retrieves a unique identifier that to identify a particular exception.
I have kept some error values and corresponding error texts in an xml file. I want to read that xml file and have to taken the error ids and fix the corresponding texts to a label. in the case of a system exception we have to identify a particular exception.
WCF / ASMX :: Difference Between Exception And Fault Exception?
Jul 18, 2010Difference between Exception and Fault Exception..?
Can i use Fault Exception when i get the Exception.
C# - Exception Is Like The Padding Is Invalid And Cannot Be Removed Exception?
Jul 12, 2010We're getting this InternalSubStringWithChecks exception with our application's healthMonitoring. This exception is like the Padding is invalid and cannot be removed exception where it's being recorded and we're getting a notification email but the end user is unaware that an actual error has happened. Though we don't want our event log filled up with this rubbish! The stack trace is:
Parameter name: length
at System.String.InternalSubStringWithChecks(Int32 startIndex, Int32 length, Boolean fAlwaysCopy)
at System.Web.Handlers.AssemblyResourceLoader.System.Web.IHttpHandler.ProcessRequest
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Console Application Calling Datalayer Throws An Exception "The Type Initializer For Threw An Exception."
Aug 17, 2010I have simple 3 tier web application and have mostly CRUDE functionalities. Recently I required to add new console application to the existing solution in which I call data layer methods for retrieving data from DB but I get an exception "The type initializer for threw an exception."When I debugged I found that the exception is thrown at datalayer on first line of class where I get connectionstring from
web.config, the code is public static readonly string CONNECT_STRING =
ConfigurationManager.ConnectionStrings["DbConnectString"].ConnectionString;
Now if I hardcode the connection string value like public static readonly string CONNECT_STRING = "Data Source=XYZ;uid=sa;password=XXX;initial catalog=ABC;"
it works fine.I don't understand what is the issue here as web application works fine with this datalayer.
Web Forms :: How To Prevent Someone From Unsubscribing Another
May 7, 2015I'm sending News Letters to my subscribers. The Email Body is equiped with "Unsubscribe" link for those wishing to.Now, assume one of my "interested" subscribers fowards the email to one of his friends. The friend will receive the email with all of its contents including that "Unsubscribe" link.If that friend clicks this link, it will forward him to my app "Unsubscribe.aspx" page carrying the info of the original email owner. Now, if that friend confirms the unsubscription, my original subscriber will end up unsubscribed!
So, is there any strategy to avoid this "hole" in the system? ... I wish if my app page "unsubscribe.aspx" can identify the source who originate the request to it and not permit "unsubscription" process if not sourced by the original email owner!
Web Forms :: How To Prevent Automatic Conversion From .CSV To .XLS
May 7, 2010I have a web page which generates a .CSV file based on some user input. When this file is downloaded by the user, the file is being automatically converted to .XLS. Any idea how I can prevent this?
For example, I am redirecting the user to the URL of the generated file, like below URL:
http://localhost/reports/Work/aa.csv
But the download window appears to download "aa.xls"!
Web Forms :: Prevent Entry Of Everything Else Except Numbers Between 0 And 120
Mar 18, 2010I have a text box (txtbx1) and a button(btnadd). Id like to use a regular expression validator or of some sort to prevent the user from continuing on the form unless its a number entered.
View 7 RepliesWeb Forms :: Prevent Reloading Page
Aug 14, 2013I visited website that it loaded very slow so I press F5 to reload page for many time after 5 or 6 time site show error that you reload page many time and didn't show website I want do it for my site that if users reload page morethan 5 time in short period of time it show error...
View 1 RepliesWeb Forms :: Prevent TreeView Postback On OnSelectedNodeChanged?
Jun 11, 2010I have a treeview loaded with nodes. When I click on a node that is set to .Selected, I want a frame to load with that node's objects. Instead, it appears that the TreeView is posting back and causing the node that was clicked to be lost. For example,setting the below function to OnSelectedNodeChanged causes a NullReferenceException.
Protected Function LoadObject(ByVal sender As Object, ByVal e As EventArgs)
Dim node As TreeNode = tv1.SelectedNode
Response.Write(node.Text.ToString())
Web Forms :: Prevent Browser Alert During Close?
Mar 9, 2011i have issue with browser close prompt;
"the webpage you are viewing is trying to close the window"
in ie6 i prevent this by using coding
self.opener = this;
self.close();
in ie7 and ie8 i prevent this by using coding
window.open('', '_self', '');
window.close();
but, problem is which code will prevent for all brower(ie6,7,8) asking the message.
Web Forms :: How To Detect And Prevent New Browser Instance
Aug 25, 2010The web app in question provides a UI for editing a client (in the business sense, not the browser sense), identified by a ClientID. I store the ClientID in Session, which gets passed from page to page, along with a number of other pieces of data in Session. Works great.
The problem is that if the user opens a new browser window using Ctrl N or File->New Window (in IE), the new window comes up with the same page as the current page, with the same session info. Then if the user navigates to a different client in the 2nd window, the ClientID in session refers to the new client. If they go back to the original browser window and save, the original client gets saved using the 2nd ClientID, and all hell breaks loose, because now the data from the two jobs are intertwined.
I have enabled trace and verified that the new browser window uses the same SessionID as the original. If an entirely new instance of IE is opened, it has a different SessionID, so is not a problem. I have not yet investigated other browsers, such as Chrome or Firefox.
Is there any way to determine if a browser instance is opened for a web app which is already open in another window or tab? Or to prevent that from happening?
Web Forms :: Prevent Copying The URL To A New Browser Window?
Dec 15, 2010My problem is am filling a form in a webpage, and click on save for instance, take the URL of mu webpage and paste it in a new window and it loads all the information I subscribed, how can I prevent that knowing that I used the Below code and it does nothing
I need to know how to add a randomly generated token as an additional parameter in my request.
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Web Forms :: Prevent Duplicate Values In Listboxes
Feb 17, 2011I have 2 listboxes, when i add a item retrieved from database to Listbox1, i need to select the item and bring it to listbox2. But i do not want to have same records added again. In my case, i cannot use the codes below
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because the text displayed on listbox1 and after transferring to listbox2 are different. So i come out with a logic which is "if listbox2 does not contain the item value in listbox1 then populate listbox2". So i tried the codes below, but it is not working as there are errors
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