NullReferenceEx ception on DataGridView.Co lumns Index property

[Kathy]

I am trying to set a tooltip for a column cell in a data grid as
documented in the MS Visual Studio 2005 documentation. I set up a test
to match the example exactly including database column, data grid
column and data values. I also have a tooltip control on the form. If
I comment out the 'if' test, it works fine, but uncommented, I get a
NullReferenceEx ception error on the
Me.dataGridView 1.Columns("Rati ng").Index reference. Here is the code
snippet from the help doc:

' Sets the ToolTip text for cells in the Rating column.
Sub dataGridView1_C ellFormatting(B yVal sender As Object, _
ByVal e As DataGridViewCel lFormattingEven tArgs) _
Handles dataGridView1.C ellFormatting

If e.ColumnIndex = Me.dataGridView 1.Columns("Rati ng").Index _
AndAlso Not (e.Value Is Nothing) Then

With Me.dataGridView 1.Rows(e.RowInd ex).Cells(e.Col umnIndex)

If e.Value.Equals( "*") Then
.ToolTipText = "very bad"
ElseIf e.Value.Equals( "**") Then
.ToolTipText = "bad"
ElseIf e.Value.Equals( "***") Then
.ToolTipText = "good"
ElseIf e.Value.Equals( "****") Then
.ToolTipText = "very good"
End If

End With

End If

End Sub 'dataGridView1_ CellFormatting
I'm new to vb.net, so be kind :-)

Thanks for the help.

[rowe_newsgroups]

Well, lets check the simple cause first. Does the column named "Rating"
exist when this code executes?

Thanks,

Seth Rowe

Kathy wrote:

I am trying to set a tooltip for a column cell in a data grid as
documented in the MS Visual Studio 2005 documentation. I set up a test
to match the example exactly including database column, data grid
column and data values. I also have a tooltip control on the form. If
I comment out the 'if' test, it works fine, but uncommented, I get a
NullReferenceEx ception error on the
Me.dataGridView 1.Columns("Rati ng").Index reference. Here is the code
snippet from the help doc:

' Sets the ToolTip text for cells in the Rating column.
Sub dataGridView1_C ellFormatting(B yVal sender As Object, _
ByVal e As DataGridViewCel lFormattingEven tArgs) _
Handles dataGridView1.C ellFormatting

If e.ColumnIndex = Me.dataGridView 1.Columns("Rati ng").Index _
AndAlso Not (e.Value Is Nothing) Then

With Me.dataGridView 1.Rows(e.RowInd ex).Cells(e.Col umnIndex)

If e.Value.Equals( "*") Then
.ToolTipText = "very bad"
ElseIf e.Value.Equals( "**") Then
.ToolTipText = "bad"
ElseIf e.Value.Equals( "***") Then
.ToolTipText = "good"
ElseIf e.Value.Equals( "****") Then
.ToolTipText = "very good"
End If

End With

End If

End Sub 'dataGridView1_ CellFormatting
I'm new to vb.net, so be kind :-)

Thanks for the help.

[Kathy]

rowe_newsgroups wrote:

Well, lets check the simple cause first. Does the column named "Rating"
exist when this code executes?

Thanks,

Seth Rowe

Yes it does. It is visible in the column properties within the
datagridview.

[rowe_newsgroups]

Are you adding the Rating Column with code or by using the "Add Column"
dialog in design view? Also what are you putting in for the Name
property and the Header Text property of the column? I used the
following in my form_load event to add the "Rating" column and
everything works fine.

DataGridView1.C olumns.Add("Rat ing", "Rating")
Dim values() As String = {"*", "**", "***", "****"}
For i As Integer = 0 To 4
DataGridView1.R ows.Add(values( i))
Next i

Let me know what you find out.

Thanks,

Seth Rowe
Kathy wrote:

rowe_newsgroups wrote:

Well, lets check the simple cause first. Does the column named "Rating"
exist when this code executes?

Thanks,

Seth Rowe

Yes it does. It is visible in the column properties within the
datagridview.

[Kathy]

rowe_newsgroups wrote:

Are you adding the Rating Column with code or by using the "Add Column"
dialog in design view? Also what are you putting in for the Name
property and the Header Text property of the column? I used the
following in my form_load event to add the "Rating" column and
everything works fine.

DataGridView1.C olumns.Add("Rat ing", "Rating")
Dim values() As String = {"*", "**", "***", "****"}
For i As Integer = 0 To 4
DataGridView1.R ows.Add(values( i))
Next i

Let me know what you find out.

Thanks,

Seth Rowe

I did not add the column in code. If I go into Edit Columns now,
Rating is one of the columns in the list. AND its properties shows
Rating as the DataPropertyNam e as well as the HeaderText.

Thanks,
Kathy

[Kathy]

I got it working by changing the following:

If e.ColumnIndex = Me.dataGridView 1.Columns("Rati ng").Index _

to:

Dim col as New DataGridViewCol umn

col = Me.dataGridView 1.Columns(e.Col umnIndex)

if col.DataPropert yName = "Rating" _
I guess Microsoft needs to correct their documentation ;)

Kathy