TCustomCachedDataSet.AfterClose Event

Occurs after an application closes a dataset.

Pascal

property AfterClose: TDataSetNotifyEvent;

C++

__property TDataSetNotifyEvent AfterClose;

Description

Write an AfterClose event handler to take specific action immediately after an application closes a dataset. For example, as a security measure, an application might clear a PASSWORD entry from the Params property of a TSQLConnection component when the dataset is closed.

AfterClose is called after a dataset is closed and the dataset state is set to dsInactive.

Delphi Examples:

Copy Code

{
This example adds an entry to a memo with a message when an
AfterOpen event or an AfterClose event occurs.  Populate the
ClientDataSet events with CheckButtonActive.
}
procedure TForm1.CheckButtonActive(DataSet: TDataSet);
begin
  if (Button1.Enabled) then
    Memo2.Lines.Add('Now that the dataset is open, record information is available.')
  else
    Memo2.Lines.Add('Now that the dataset is closed, record information is not available.');
  Button1.Enabled := not ClientDataSet1.Active;
  Button2.Enabled := ClientDataSet1.Active;
  Button3.Enabled := ClientDataSet1.Active;
end;

Copy Code

{
The following code fragment illustrates how DataSets and
DataSetCount can be used to ensure that an action is taken
for every open dataset.  Assign CheckButtonActive as the
AfterClose and AfterOpen event handlers for TClientDataSet1.
}
procedure TForm1.Button1Click(Sender: TObject);
var
  I: Integer;
begin
  if not RemoteServer1.Connected then
    RemoteServer1.Connected := True;
  ClientDataSet1.Close;
  with RemoteServer1 do
  begin
    for I := 0 to DataSetCount - 1 do
      DataSets[I].EnableControls;
  end;
  ClientDataSet1.Open;
end;

procedure TForm1.Button3Click(Sender: TObject);
var
  I: Integer;
begin
  ClientDataSet1.Close;
  RemoteServer1.Connected := False;
  with RemoteServer1 do
  begin
    for I := 0 to DataSetCount - 1 do
      DataSets[I].DisableControls;
  end;
end;

procedure TForm1.CheckButtonActive(DataSet: TDataSet);
begin
  Button1.Enabled := not ClientDataSet1.Active;
  Button2.Enabled := ClientDataSet1.Active;
  Button3.Enabled := ClientDataSet1.Active;
end;