Null reference object exception

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VB

If e.Row.RowType = DataControlRowType.Header Then
            Dim ddlVCrop As New DropDownList
            ddlVCrop = CType(e.Row.FindControl("ddlCrop"), DropDownList)
            If Not ddlVCrop Is DBNull.Value Then
                Dim ds As New DataSet
                ds = objYield.getVariety
                If ds.Tables(0).Rows.Count > 0 Then
                 ddlVCrop.DataSource = ds
                    ddlVCrop.DataValueField = "VARIETY_CODE"
                    ddlVCrop.DataTextField = "VARIETY_CODE"
                    ddlVCrop.DataBind()
                    ddlVCrop.Items.Insert(0, "Select One")
                   
End If

Hi

In the above code when i am trying to bind the "ds" to "dropdown"(in the sentence in bold), i am facing null reference exception.Any one plz tell me the solution to my problem.

thanks in advance.
[edit]code block added[/edit]

Posted 11-Apr-11 1:40am

Harsha 2

Updated 11-Apr-11 1:52am

#realJSOP

v3

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Venkatesh Mookkan · Answer 1 · 2011-04-11T01:55:00

Solution 1

Change the code to,

VB

If ddlVCrop IsNot Nothing Then

Posted 11-Apr-11 1:55am

Venkatesh Mookkan

Comments

Harsha 2 11-Apr-11 8:09am

Tnx for reply,

By adding the solution you have suggested I am able to handle the exception.But my concern is to bind the dataset to dropdown in the GridView dynamically which is not happening. So plz guide me in that aspect.

Venkatesh Mookkan 11-Apr-11 9:21am

I have a feeling that your GridView row does not have a DropDownList named "ddlCrop". Please cross verified. It is better to diagnose if you post your ASPX code too.

#realJSOP · Answer 2 · 2011-04-11T01:57:00

Solution 2

To avoid the exception, I'd do this:

VB

Dim ds As DataSet = objYield.getVariety()
If ds IsNot Nothing AndAlso ds.Tables.Count > 0 AndAlso ds.Tables(0).Rows.Count > 0 Then
   ... do your processing
End If

Posted 11-Apr-11 1:57am

#realJSOP

Mahendra.p25 · Answer 3 · 2011-04-11T02:02:00

Solution 3

i think your drodown is in gridview header template

try to find out your dropdown in this way

GridView1.HeaderRow.FindControl("DropDownList1")

Posted 11-Apr-11 2:02am

Mahendra.p25

Abhinav S · Answer 4 · 2011-04-11T02:15:00

Solution 5

Something appears to be null here.
Try debugging through your code, have a look at the values of the underlying variables and perhaps you will be able to figure out what is really wrong (why this value is null).

Posted 11-Apr-11 2:15am

Abhinav S

Comments

Harsha 2 11-Apr-11 8:49am

Tnx for reply,
Could you explain the need of giving "data key names" in the gridview inline editing.

Harsha 2 · Answer 5 · 2011-04-11T02:09:00

Solution 4

By adding the solution you have suggested I am able to handle the exception.But my concern is to bind the dataset to dropdown in the GridView dynamically which is not happening. So plz guide me in that aspect.

Posted 11-Apr-11 2:09am

Harsha 2