Datagridview doesn't update current row values

[Phil]

VB2008
I have a DataGridView with MultiSelect = True and
SelectionMode=FullRowSelect. One of the columns is a checkbox column. I have
a function that goes through all the selected rows and sets the value of
this column.

For Each row In DataGridView1.SelectedRows
row.Cells("MyCheckboxColumn").Value = False
Next

This seems to almost work, but I noticed that sometimes it does not update
the first or the last selected row. On investigation, it seems that the
value is updated, but if the row happens to be the currentrow, the change is
not displayed until the currentrow is changed. I have managed to get around
this problem by setting CurrentCell = Nothing after I have made the changes,
but this has the undesirable side effect of clearing the selection.

Any suggestions?

TIA
Phil.

[Linda Liu[MSFT]]

Hi Phil,

I performed a test based on your description but didn't reproduce the
problem on my side. All selected rows in the DataGridView are updated
immediately in my test application.

I create a WinForm Application project in VS2008 and add a DataGridView and
a Button on the Form1. I add a DataGridViewCheckBoxColumn in the
DataGridView. The following is the code in the Form1.vb:

Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
Me.DataGridView1.SelectionMode =
DataGridViewSelectionMode.FullRowSelect
Me.DataGridView1.RowCount = 10
For i As Integer = 0 To 9
Me.DataGridView1.Rows(i).Cells(0).Value = True
Next
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
For Each row As DataGridViewRow In Me.DataGridView1.SelectedRows
row.Cells(0).Value = False
Next
End Sub
End Class

Build and run the application. Select some rows in the DataGridView with
Mouse and click the Button, all selected rows are updated immediately.
Is there any difference between your code and mine?

Sincerely,
Linda Liu
Microsoft Online Community Support

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[Phil]

"Linda Liu[MSFT]" <v-****@online.microsoft.comwrote in message
news:Fj**************@TK2MSFTNGHUB02.phx.gbl...

Hi Phil,

I performed a test based on your description but didn't reproduce the
problem on my side. All selected rows in the DataGridView are updated
immediately in my test application.

Thanks for looking at this. My datagridview is part of a larger application,
so there is quite a lot of difference from your code. I shall try to
reproduce the problem in a smaller app. The main thing that springs to mind
that is different is that my data is populated from a datasource (OleDb -
access/jet). I'm not sure if that is relevant.

Phil.

[Phil]

"Linda Liu[MSFT]" <v-****@online.microsoft.comwrote in message
news:Fj**************@TK2MSFTNGHUB02.phx.gbl...

Hi Phil,

I performed a test based on your description but didn't reproduce the
problem on my side. All selected rows in the DataGridView are updated
immediately in my test application.

OK. I have managed to adapt your code to reproduce the problem.
Create the datagridview initially with no columns and replace Form_Load
as follows:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load

Me.DataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect

Dim data As New DataTable
data.Columns.Add("Column1", Type.GetType("System.Int16"))
For i As Integer = 0 To 9
data.Rows.Add(1)
Next

Me.DataGridView1.DataSource = data

Dim col As New DataGridViewCheckBoxColumn
Me.DataGridView1.Columns.Add(col)
col.DataPropertyName = "Column1"

End Sub

[Phil]

OK. I have managed to adapt your code to reproduce the problem.

Create the datagridview initially with no columns and replace Form_Load
as follows:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load

Me.DataGridView1.SelectionMode =
DataGridViewSelectionMode.FullRowSelect

Dim data As New DataTable
data.Columns.Add("Column1", Type.GetType("System.Int16"))
For i As Integer = 0 To 9
data.Rows.Add(1)
Next

Me.DataGridView1.DataSource = data

Dim col As New DataGridViewCheckBoxColumn
Me.DataGridView1.Columns.Add(col)
col.DataPropertyName = "Column1"

End Sub

It seems the problem occurs when there are two columns bound to the same
data property.
If I add:
Me.DataGridView1.Columns.Remove("Column1")
The problem does not occur.

In my main application I hide this column. I shall try removing it instead,
and see if that fixes it.
It does seem to be a bug in the datagridview data binding though.

[Phil]

In my main application I hide this column. I shall try removing it
instead,
and see if that fixes it.

It didn't fix it :-(
Not sure why, perhaps because there are other columns too.

[Phil]

It seems the problem occurs when there are two columns bound to the same
data property.

The reason I am doing this, is because the column does not automatically
appear as a checkbox. The underlying SQL query is of the following form:

SELECT EXISTS(subquery), ....

For some reason the result of the EXISTS function seems to come back as an
integer in the Dataset. If there was some way to make this return a boolean,
that might solve my problem. This is OleDb (access/jet).

[Linda Liu[MSFT]]

Hi Phil,

Thank you for your prompt reply!

I performed a test based on your sample code and did reproduce the problem
on my side. If I update the data in the data source in code directly, the
problem also exists even if there's only one DataGridViewCheckBoxColumn in
the DataGridView.

This problem is not relevant to multiple columns' being bound to the same
data property.

The reason behind this problem is that data binding doesn't refresh data of
the current item in UI when the data in the underlying data source are
changed.

The workaround is to call the EndCurrentEdit method of the corresponding
BindingManagerBase object associated with the data source to end current
edit to the data source and refresh the UI.

For example, after you change the value of the DataGridViewCells or change
the data in the data source directly, add the following line of code:
Me.BindingContext(data).EndCurrentEdit()

For some reason the result of the EXISTS function seems to come back as

an integer in the Dataset.

The EXISTS operator returns a value of bit. In .NET, the corresponding type
is Boolean. If a data column is of type Boolean, DataGridView will generate
a DataGridViewCheckBoxColumn for this data column.

Is the DataTable strong-typed in your application? If so, you may open the
DataSet in the designer and select the column of the DataTable and check
the column's type in the Properties window. If not, you need to set a break
point in your code and press F5 to run the application. When the
application enters into break mode, you can check the type of the
DataTable's column.

Hope this helps.
If you have any question, please feel free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support

Delighting our customers is our #1 priority. We welcome your comments and
suggestions about how we can improve the support we provide to you. Please
feel free to let my manager know what you think of the level of service
provided. You can send feedback directly to my manager at:
ms****@microsoft.com.

This posting is provided "AS IS" with no warranties, and confers no rights.

[Linda Liu[MSFT]]

Hi Phil,

How about the problem now?

If you have any question, please feel free to let me know.

Thank you for using our MSDN Managed Newsgroup Support Service!

Sincerely,
Linda Liu
Microsoft Online Community Support

Delighting our customers is our #1 priority. We welcome your comments and
suggestions about how we can improve the support we provide to you. Please
feel free to let my manager know what you think of the level of service
provided. You can send feedback directly to my manager at:
ms****@microsoft.com.

This posting is provided "AS IS" with no warranties, and confers no rights.

[Phil]

How about the problem now?

Hello Linda,

Thanks for your reply. I was away on holiday last week, and am just catching
up with messages. I shall take a look in more detail later.

Thanks,
Phil.

[Phil]

I performed a test based on your sample code and did reproduce the problem

on my side. If I update the data in the data source in code directly, the
problem also exists even if there's only one DataGridViewCheckBoxColumn in
the DataGridView.

OK.

>
This problem is not relevant to multiple columns' being bound to the same
data property.

OK. That was just a theory :-)

>
The reason behind this problem is that data binding doesn't refresh data
of
the current item in UI when the data in the underlying data source are
changed.

OK. That makes sense I think. It still thinks the row is being edited, so
doesn't refresh until the current row is changed.

>
The workaround is to call the EndCurrentEdit method of the corresponding
BindingManagerBase object associated with the data source to end current
edit to the data source and refresh the UI.

OK.

>
For example, after you change the value of the DataGridViewCells or change
the data in the data source directly, add the following line of code:
Me.BindingContext(data).EndCurrentEdit()

I'll try that. Thanks.

>

>For some reason the result of the EXISTS function seems to come back as

an integer in the Dataset.

The EXISTS operator returns a value of bit. In .NET, the corresponding
type
is Boolean. If a data column is of type Boolean, DataGridView will
generate
a DataGridViewCheckBoxColumn for this data column.

Is the DataTable strong-typed in your application?

No.

If so, you may open the
DataSet in the designer and select the column of the DataTable and check
the column's type in the Properties window. If not, you need to set a
break
point in your code and press F5 to run the application. When the
application enters into break mode, you can check the type of the
DataTable's column.

I think I have done this, and IIRC it was returning Int16. I'll check this
again tomorrow.

>

Thanks for your help.
Phil.

[Phil]

>

>For example, after you change the value of the DataGridViewCells or
change
the data in the data source directly, add the following line of code:
Me.BindingContext(data).EndCurrentEdit()

I'll try that. Thanks.

>>

BindingContext(MyDataGridView.DataSource).EndCurre ntEdit()
That did the trick.
Thanks
Phil.

[Linda Liu[MSFT]]

Hi Phil,

Thank you for your feedback! I'm glad to hear that the problem is solved
now.

If you have any other questions in the future, please don't hesitate to
contact us. It's always our pleasure to be of assistance!

Have a good day!

Sincerely,
Linda Liu
Microsoft Online Community Support

Delighting our customers is our #1 priority. We welcome your comments and
suggestions about how we can improve the support we provide to you. Please
feel free to let my manager know what you think of the level of service
provided. You can send feedback directly to my manager at:
ms****@microsoft.com.

This posting is provided "AS IS" with no warranties, and confers no rights.

[Phil]

Thank you for your feedback! I'm glad to hear that the problem is solved

now.

Unfortunately, I've just discovered a side-effect of this fix which is going
to cause me some problems :-(
I have some code which checks whether any changes have been made to the
data, and of course now after using EndCurrentEdit, the HasChanges property
of the Dataset now returns False. I guess I'll have to maintain my own
status flag now to do this.

[Phil]

Unfortunately, I've just discovered a side-effect of this fix which is

going to cause me some problems :-(
I have some code which checks whether any changes have been made to the
data, and of course now after using EndCurrentEdit, the HasChanges
property of the Dataset now returns False. I guess I'll have to maintain
my own status flag now to do this.

This seems to do the trick:

BindingContext(MyDataGridView.DataSource).EndCurre ntEdit()
MyDataGridView.DataSource.Rows(0).BeginEdit()

This forces the display to update correctly after I update the data, and
HasChanges still returns True.
Is this likely to cause any problems? This code may be called a number of
times, and I never call AcceptChanges because I am not using the DataSource
to commit the changes made to the data.

[Phil]

>Is the DataTable strong-typed in your application?

No.

>If so, you may open the
DataSet in the designer and select the column of the DataTable and check
the column's type in the Properties window. If not, you need to set a
break
point in your code and press F5 to run the application. When the
application enters into break mode, you can check the type of the
DataTable's column.

I think I have done this, and IIRC it was returning Int16. I'll check this
again tomorrow.

>>

Dataset.Tables(0).Columns(MyColumn).DataType:
{Name = "Int16" FullName = "System.Int16"} System.Type

MyDataSet.Tables(0).Rows(0).Item(MyColumn):
-1 {Short} Object

The sql is of the form:

SELECT ... , Exists(subquery), ....

the database is Access/Jet (mdb) and I'm using an OleDbConnection and
OleDBAdapter to execute the query and populate the Dataset.

[Linda Liu[MSFT]]

Hi Phil,

>... now after using EndCurrentEdit, the HasChanges property of the Dataset

now returns False.

I performed a test on this but didn't reproduce the problem on my side. The
HasChanges method of the DataSet still returns true after I call the
EndCurrentEdit method on the associated BindingManagerBase object.

In fact, only after we call the DataSet.AcceptChanges method, the
HasChanges method will return false.

the database is Access/Jet (mdb) and I'm using an OleDbConnection and

OleDBAdapter to execute the query and populate the Dataset.

If you drag the database table from Server Explorer and drop it onto the
DataSet designer, what's the data type of the data column in question?

If the data column's data type is still Int16, a workaround is to change
the type to Boolean in code by yourself.

Hope this helps.

Sincerely,
Linda Liu
Microsoft Online Community Support

Delighting our customers is our #1 priority. We welcome your comments and
suggestions about how we can improve the support we provide to you. Please
feel free to let my manager know what you think of the level of service
provided. You can send feedback directly to my manager at:
ms****@microsoft.com.

This posting is provided "AS IS" with no warranties, and confers no rights.

[Linda Liu[MSFT]]

Hi Phil,

How about the problem now?

If you have any question, please feel free to let me know.

Thank you for using our MSDN Managed Newsgroup Support Service!

Sincerely,
Linda Liu
Microsoft Online Community Support

Delighting our customers is our #1 priority. We welcome your comments and
suggestions about how we can improve the support we provide to you. Please
feel free to let my manager know what you think of the level of service
provided. You can send feedback directly to my manager at:
ms****@microsoft.com.

This posting is provided "AS IS" with no warranties, and confers no rights.

[Phil]

>

>>... now after using EndCurrentEdit, the HasChanges property of the Dataset

now returns False.

I performed a test on this but didn't reproduce the problem on my side.
The
HasChanges method of the DataSet still returns true after I call the
EndCurrentEdit method on the associated BindingManagerBase object.

That's odd.

>
In fact, only after we call the DataSet.AcceptChanges method, the
HasChanges method will return false.

That's what I would have expected.

>

>the database is Access/Jet (mdb) and I'm using an OleDbConnection and

OleDBAdapter to execute the query and populate the Dataset.

If you drag the database table from Server Explorer and drop it onto the
DataSet designer, what's the data type of the data column in question?

I am not using the database designer in this project. I have some generic
code that I pass a SQL query to. This uses an OleDbConnection and
OleDbDataAdapter to generate a DataSet object.

>
If the data column's data type is still Int16, a workaround is to change
the type to Boolean in code by yourself.

I can perhaps try this, although I want to avoid having to create separate
classes for each of the different database queries in my project.

[Phil]

"Phil" <N/Awrote in message
news:p8******************************@posted.plusn et...

>>>... now after using EndCurrentEdit, the HasChanges property of the
Dataset

now returns False.

I performed a test on this but didn't reproduce the problem on my side.
The
HasChanges method of the DataSet still returns true after I call the
EndCurrentEdit method on the associated BindingManagerBase object.

That's odd.

I wonder if this is because I have two columns both bound to the same item?
Only one of them has been changed, and this might cause some confusion.
I am not too concerned, as my workaround seems OK for now.

[Linda Liu[MSFT]]

Hi Phil,

Thank you for your reply!

I wonder if this is because I have two columns both bound to the same

item? Only one of them has been changed, and this might cause some
confusion.

No, I don't think so. You may create a new WinForm application project to
perform a test on it, if you'd like to.

I am not too concerned, as my workaround seems OK for now.

Well, I consider I can close this issue in the newsgroup now. Do you agree
with me? If you have any concern, please feel free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support

Delighting our customers is our #1 priority. We welcome your comments and
suggestions about how we can improve the support we provide to you. Please
feel free to let my manager know what you think of the level of service
provided. You can send feedback directly to my manager at:
ms****@microsoft.com.

This posting is provided "AS IS" with no warranties, and confers no rights.