using GetChanges on a datatable

[Sam]

Hi,
I have a datagrid which source is a dataset :

dgFields.Rows.DataMember = m_dsFields.Tables(0).TableName
dgFields.Rows.DataSource = m_dsFields

Now my values are displayed properly and when I add a row I call the
follwing :

Dim dtChanged As New DataTable
dtChanged = m_dsFields.Tables(0).GetChanges(DataRowState.Added)

but dtChanged is always equal to Nothing.

What am I doing wrong ?

thx

 

[Cor Ligthert]

Sam,

Can you show how you show us how you add the datarow, yesterday there was
somebody who thought he added it, however that was not done, there was alone
a new datarow created.

Cor

 

[Sam]

humm...
To be honnest I don't add anything. At the bottom of my datagrid there
is a new line so I fill in the txtboxes and that's it. I would assume
then that the changes made to the datagrid are reflected on to the
datasource, but I might be wrong.

The code above is all I do. What is missing ?

 

[Sam]

Actually it might be important that I mention that I've tried the exact
same code with the parameters DataRowState.Modified and
DatarowState.Deleted, and that in both cases, my dtChanged is filled
with the right lines !!!!
Therefore I believe my code is correct, however something is wrong with
DatarowState.Added or I'm missing something here !

 

[Cor Ligthert]

Sam,

You add probably a row using the datagrid.

Set this before your get changes than probably it will go.

\\\
BindingContext(m_dsFields.Tables(0)).EndCurrentEdit
///
This pushes the changes from the datagrid into the dataset when there has
not been a rowchange.


I hope this helps,

Cor

 

[Sam]

Cor,
I've done that:
Dim dtChanged As New DataTable
BindingContext(m_dsFields.Tables(0)).EndCurrentEdit()
dtChanged = m_dsFields.Tables(0).GetChanges(DataRowState.Added)

But dtChanged is still Nothing I really don't understand why. That's
a pain !
What does BindingContext here ?

 

[Sam]

Cor,
Actually I've noticed that it works with DataRowState.Modified. I mean
that even newly added rows are contained in dtChanged. I guess I can
use that if I can't get the Added method to work

 

[Cor Ligthert]

Sam,

Try this sample partially with your code, I had not any problem, it works
in my opinion as you and I would expect.


\\\needs a datagrid and a button on a form
Dim dt As New DataTable
Private Sub Form1_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load
dt.Columns.Add("Place")
dt.Columns.Add("Name")
dt.Columns.Add("Key")
dt.LoadDataRow(New Object() {"Whatever", "Sam", "1"}, True)
dt.LoadDataRow(New Object() {"Whatelse", "Cor", "2"}, True)
DataGrid1.DataSource = dt
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button1.Click
Dim dtChanged As New DataTable
BindingContext(dt).EndCurrentEdit()
dtChanged = dt.GetChanges(DataRowState.Added)
DataGrid1.DataSource = Nothing
DataGrid1.DataSource = dtChanged
End Sub
///
I hope this helps,

Cor

 

[Sam]

Thx Cor,
unfortunately it doesn't work for me. My dtChanged is still Nothing....
I'm giving up, I will use DataRowState.Modified instead...

 

[Cor Ligthert]

Sam,

unfortunately it doesn't work for me. My dtChanged is still Nothing....
I'm giving up, I will use DataRowState.Modified instead...

Did you try my sample, because it shows that dtChanged in the datagrid.

Cor

 

[Sam]

well I've tried your code in my program :

Dim dtChanged As New DataTable
BindingContext(m_dsFields.Tables(0)).EndCurrentEdit()

dtChanged = m_dsFields.Tables(0).GetChanges(DataRowState.Added)
dgFields.Rows.DataSource = Nothing
dgFields.Rows.DataSource = dtChanged

and unfortunately dtChanged still is Nothing !

 

[Cor Ligthert]

Sam,

However as in my first question, how you are so sure you added a row?

Cor

 

[Sam]

I'd like to know what you mean by 'adding a row'.
I add stuff in my cells of the last row of my datagrid (the one marked
by a *)

From the moment I add things in this row, I would assume that the

datasource of this grid should be modified (in fact
DataRowState.Modified works) but apparentely it doesn't detect an added
row

Sam.

 

[Cor Ligthert]

Sam,

Why not try my sample complete?

Cor

 

[Sam]

Because I trust you, I know your code is working, but the thing is that
my code is the same as yours !

 

[Cor Ligthert]

Sam,

There is a new Pope, that is not a miracle, so what is the miracle here.

What Net version are you using.

Cor

 

[Cor Ligthert]

Are you sure that you click the star

enter data
click the pencil

Cor

 

[Sam]

er.. no I didn't know I had to click the pencil ..... I'll try
thx

 

[Sam]

Cor,
I've tried that but dtChanged is still nothing.
my code :

Dim dtChanged As New DataTable
BindingContext(m_dsFields.Tables(0)).EndCurrentEdit()
dtChanged = m_dsFields.Tables(0).GetChanges(DataRowState.Added)
dgFields.Rows.DataSource = Nothing
dgFields.Rows.DataSource = dtChanged

The thing to note here is that m_dsFields contains the new row ! But
dtChanged does not. So this is weird. Maybe I should have mentionned
that I'm not using the microsoft datagrid but a third party control
(FlyGrid). However this control should not have any influence on
DataRowState.Added and as I said, m_dsFields is properly modified
anyway.

 

[Cor Ligthert]

Sam,

Why not try it with a normal grid and otherwise.

dtChanged = m_dsFields.Tables(0).GetChanges(DataRowState.Added) messagebox.show(dtChanged.Rows.Count.ToString)

dgFields.Rows.DataSource = Nothing
dgFields.Rows.DataSource = dtChanged

Cor