Object reference not set to an instance of an object.

Question

3.00/5 (1 vote)

See more:

VB

Dim CustomerID As String = DirectCast(GridView1.Rows(e.RowIndex).FindControl("lblCustomerID"), TextBox).Text
       Dim Name As String = DirectCast(GridView1.Rows(e.RowIndex).FindControl("txtName"), TextBox).Text
       Dim Company As String = DirectCast(GridView1.Rows(e.RowIndex).FindControl("txtCompany"), TextBox).Text

       Dim con As New SqlConnection(ConfigurationManager.ConnectionStrings("connectionstring").ConnectionString)
       con.Open()

       Dim update As String = "update customer set Name=@Name,Company=@Company where CustomerID=@CustomerID" & "select * from customer"
       Dim adp As SqlDataAdapter = New SqlDataAdapter(update, con)
       adp.UpdateCommand.Parameters.AddWithValue("@Name", Name)
       adp.UpdateCommand.Parameters.AddWithValue("@Company", Company)
       adp.UpdateCommand.Parameters.AddWithValue("@CustomerID", CustomerID)
       GridView1.EditIndex = -1
       con.Close()
       BindData()

VB

Private Sub BindData()
    Dim con As New SqlConnection(ConfigurationManager.ConnectionStrings("connectionstring").ConnectionString)
    Dim Selectquery As String = "select * from customer"
    '  Dim cmd As SqlCommand = New SqlCommand(Selectquery, con)
    Dim adp As SqlDataAdapter = New SqlDataAdapter(Selectquery, con)
    Dim datatable As New DataTable
    adp.Fill(datatable)
    GridView1.DataBind()
End Sub

Getting an error
Object reference not set to an instance of an object.

SQL

adp.UpdateCommand.Parameters.AddWithValue("@Name", Name)
but i think there is a problem with typecasting which i have done in 1st line

Posted 27-Sep-13 3:19am

Member 10284688

Updated 27-Sep-13 3:30am

v2

Add a Solution

Comments

[no name] 27-Sep-13 9:24am

Okay well debug your code, find out which line has the object that is Nothing and fix it. Then you will need to fix your SQL too.

Member 10284688 27-Sep-13 9:27am

adp.UpdateCommand.Parameters.AddWithValue("@Name", Name)
but i think there is a problem with typecasting which i have done in 1st line

[no name] 27-Sep-13 9:32am

The name that you have given indicates that the control is a label not a textbox.

Member 10284688 27-Sep-13 9:35am

Dim CustomerID As String = DirectCast(GridView1.Rows(e.RowIndex).FindControl("lblCustomerID"), Label).Text
Unable to cast object of type 'System.Web.UI.WebControls.TextBox' to type 'System.Web.UI.WebControls.Label'.

Sergey Alexandrovich Kryukov 27-Sep-13 9:24am

In what line?
—SA

Member 10284688 27-Sep-13 9:27am

adp.UpdateCommand.Parameters.AddWithValue("@Name", Name)
but i think there is a problem with typecasting which i have done in 1st line

Sergey Alexandrovich Kryukov 27-Sep-13 9:35am

It may or may not be the problem, depending on actual runtime type. But then the exception would be in that line, and you would not get exception on the line you show: "apd" can be null, otherwise "apd.UpdateCommand". It this is that line, put a break point and see what happens...
—SA

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sergey Alexandrovich Kryukov · Answer 1 · 2013-09-27T03:36:00

Okay, you are not really sure where the exception "Object reference not set to an instance of an object" is thrown.

Not to worry. This is one of the very easiest cases to detect and fix. It simply means that some member/variable of some reference type is dereferenced by using and of its instance (non-static) members, which requires this member/variable to be non-null, but in fact it appears to be null. Simply execute it under debugger, it will stop the execution where the exception is thrown. Put a break point on that line, restart the application and come to this point again. Evaluate all references involved in next line and see which one is null while it needs to be not null. After you figure this out, fix the code: either make sure the member/variable is properly initialized to a non-null reference, or check it for null and, in case of null, do something else.

Please see also: want to display next record on button click. but got an error in if condition of next record function "object reference not set to an instance of an object"[^].

Sometimes, you cannot do it under debugger, by one or another reason. One really nasty case is when the problem is only manifested if software is built when debug information is not available. In this case, you have to use the harder way. First, you need to make sure that you never block propagation of exceptions by handling them silently (this is a crime of developers against themselves, yet very usual). The you need to catch absolutely all exceptions on the very top stack frame of each thread. You can do it if you handle the exceptions of the type System.Exception. In the handler, you need to log all the exception information, especially the System.Exception.StackTrace:
http://msdn.microsoft.com/en-us/library/system.exception.aspx[^],
http://msdn.microsoft.com/en-us/library/system.exception.stacktrace.aspx[^].

The stack trace is just a string showing the full path of exception propagation from the throw statement to the handler. By reading it, you can always find ends. For logging, it's the best (in most cases) to use the class System.Diagnostics.EventLog:
http://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog.aspx[^].

Good luck,

—SA