TDataSet.AfterOpen Event

Occurs after an application completes opening a dataset and before any data access occurs.

Pascal

property AfterOpen: TDataSetNotifyEvent;

C++

__property TDataSetNotifyEvent AfterOpen;

Description

Write an AfterOpen event handler to take specific action immediately after an application opens the dataset. AfterOpen is called after the dataset establishes access to its data and the dataset is put into dsBrowse state. For example, an AfterOpen event handler might check an ini file to determine the last record touched in the dataset the previous time the application ran, and position the dataset at that record.

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;