Check if new data is already exist in dynamic-created-checkboxlist

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I created a dynamic checkbox at Page Load (Not isPostback)

Now if a new data is to be inserted, the system should check first whether the data is already exist in the created checkboxlist.

i have tried this, but error occured

Object reference not set to an instance of an object.

This is my code.

VB

Dim row As DataRow = dt.NewRow()

  Dim chlist As CheckBoxList = DirectCast(FindControl("cbTest"), CheckBoxList)
      For i = 0 To dtSH.Rows.Count - 1

        For Each Listdata As ListItem In chlist.Items

            For Each row1 As DataRow In dt.Rows

               If dtSH.Rows(i)("EMPID_T") <> row1("EMPID_T").ToString Then
                             row = dt.NewRow()
                             row("EMPID_T") = dtSH.Rows(i)("EMPID_T")
                             row("NAME_T") = dtSH.Rows(i)("NAME_T")
                             dt.Rows.Add(row)
                         End If

                     Next
                 Next

             Next

i dont know whether here

VB

Dim chlist As CheckBoxList = DirectCast(FindControl("cbTest"), CheckBoxList)

or here

VB

For Each Listdata As ListItem In chlist.Items

that goes wrong. A little help please. TQ!

Posted 26-Jul-12 18:57pm

snamyna

Updated 26-Jul-12 22:53pm

v2

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Sandeep Mewara · Answer 1 · 2012-07-29T08:29:00

Object reference not set to an instance of an object

This error happens when you try to use a property or call a method of an object that is null. More details: here[^]

A simple use of Visual studio DEBUGGER can tell you the object because of which it is happening. Just look at the stack trace and put a debugger on that line. Check the objects of that line and see if any one is null and you are trying to use that objects property. Handle the same.

graciax8 · Answer 2 · 2012-07-26T23:14:00

Solution 1

where is the declaration of i?

mark as answer if it helped you. :)

Posted 26-Jul-12 23:14pm

graciax8

Comments

snamyna 27-Jul-12 5:29am

I just paste some piece of my code.
The error points here "For Each Listdata As ListItem In chlist.Items"

graciax8 27-Jul-12 6:03am

it is right.

snamyna 27-Jul-12 6:15am

I think the error source is here
"Dim chlist As CheckBoxList = DirectCast(FindControl("cbTest"), CheckBoxList)"
because when I debug, chlist is nothing.
How is it actually to pass cbTest properties and datatable into chlist?