Grid View Row updating

Object Reference not set to an instance.

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1 Replies - 17813 Views - Last Post: 12 July 2010 - 09:00 AM Rate Topic: -----

#1 krisssgopi   User is offline

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Grid View Row updating

Posted 09 July 2010 - 10:17 PM

Hi Team,

Am using Grid View in ASP.Net while am trying to update the row it was not getting updated. Instead, it throw an exception Object reference not set to an instance. please help me in this regard.

Protected Sub GridView1_RowUpdating(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewUpdateEventArgs) Handles GridView1.RowUpdating
            Dim txtName, txtName1, txtName2, txtname3 As New TextBox
            Dim row As GridViewRow = GridView1.Rows(e.RowIndex)
            txtName = CType(row.FindControl("txtName"), TextBox)
            txtName1 = CType(row.FindControl("txtName1"), TextBox)
            txtName2 = CType(row.FindControl("txtName2"), TextBox)
            txtname3 = CType(row.FindControl("txtName3"), TextBox)

            'doupdate(txtName1, txtName2, txtname3, txtName)
            cmd = New MySqlCommand("update login set username='" & txtName1.Text & "',password='" & txtName2.Text & "',Usertype='" & txtname3.Text & "' where id='" & txtName.Text & "')", con)
            da = New MySqlDataAdapter(cmd)
            ds = New DataSet
            GridView1.DataSource = ds
        Catch ex As Exception
        End Try
    End Sub

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Replies To: Grid View Row updating

#2 Frinavale   User is offline

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Re: Grid View Row updating

Posted 12 July 2010 - 09:00 AM

You are retrieving TextBoxes from the row using the FindControl command.
The FindControl method may not have been able to retrieve a TextBox though and so it will return Nothing. You should always check to make sure that the controls that you are retrieving exist before you attempt to use them.

For example, the following will check to make sure that "txtName" exists:
If txtName IsNot Nothing Then
  'txtName was successfully is not nothing
  'you can use it without experiencing a Null Reference Exception
  'something went wrong and txtName does not exist 
End If

Are you sure that the IDs of the TextBoxes are correct?


(PS you should be using parameters to create your SQL should not be dynamically creating your SQL statement by concatenating user provided data into your SQL command because this leaves you open to a SQL Injection Attack)
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