[Theprasit]

Hi,

just sent you a testing code that result in an error.
This is a N-Tier application that prepare data on server side and transfer as stream over network to client side.
On client side I used kbmMemTable to load data from stream as use as working table then send update data back to server.

If you run Button1Click, it’s result in error “mt1: cannot perform this operation on closed dataset”.
If you run Button2Click, it’s just fined, a calculation field is created as expect.

I use almost default properties of kbmMemTable and related class (default after create).
Do I miss anything to fine tune?

Regards,

procedure TForm5.Button1Click(Sender: TObject);
var
mt_fmt: TkbmBinaryStreamFormat;
ms: TMemoryStream;
begin
mt_fmt:= TkbmBinaryStreamFormat.Create(nil);
ms:= TMemoryStream.Create;
try
// ut is a TUniDacTable which load data from DataBase
// this part is done on server side and sent a stream over network
mt2.LoadFromDataSet(ut, [mtcpoStructure]);
mt2.SaveToStreamViaFormat(ms, mt_fmt);
ms.Position:= 0;

// this is on client side which get a stream and load back to kbmMemTable
// mt_fmt on server and client used same properties (default after create)
mt1.LoadFromStreamViaFormat(ms, mt_fmt);

finally
mt_fmt.Free;
ms.Free;
end;
dsMem.DataSet:= mt1;

// *** this method got error "mt1: Canoot perform this operation on closed dataset"
end;

procedure TForm5.Button2Click(Sender: TObject);
var
mt_fmt: TkbmBinaryStreamFormat;
ms: TMemoryStream;
begin
mt_fmt:= TkbmBinaryStreamFormat.Create(nil);
ms:= TMemoryStream.Create;
try
// ut is a TUniDacTable which load data from DataBase
// this part is done on server side and sent a stream over network
mt2.LoadFromDataSet(ut, [mtcpoStructure]);
mt2.SaveToStreamViaFormat(ms, mt_fmt);
ms.Position:= 0;

// this is on client side which get a stream and load back to kbmMemTable
// mt_fmt on server and client used same properties (default after create)
mt3.LoadFromStreamViaFormat(ms, mt_fmt);

// mt3 is a temporary kbmMemTable use as my work around solution
mt1.LoadFromDataSet(mt3, [mtcpoStructure]);

// *** this method run without error, a calculation field is created as expect
finally
mt_fmt.Free;
ms.Free;
end;
dsMem.DataSet:= mt1;
end;

procedure TForm5.mt1BeforeOpen(DataSet: TDataSet);
var
fl: TField;
begin
mt1.FieldDefs.Update;
for var ix:= 0 to mt1.FieldDefs.Count- 1 do
mt1.FieldDefs[ix].CreateField(mt1);

fl:= TStringField.Create(mt1);
fl.FieldName:= 'Calc';
fl.FieldKind:= fkCalculated;
fl.DataSet:= mt1;
end;

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