TDataSet.EnableControls Method

Re-enables data display in data-aware controls associated with the dataset.

Pascal

procedure EnableControls;

C++

__fastcall EnableControls();

Description

Call EnableControls to permit data display in data-aware controls after a prior call to DisableControls. EnableControls decrements the disabled count variable for the dataset if it is not already zero. If the disable count variable is zero, EnableControls updates the current state of the dataset, if necessary, and then tells associated controls to re-enable display.

Delphi Examples:

Copy Code

{
Usually DisableControls is called within the context of a
try...finally block that reenables the controls even if an
exception occurs. For example:
} 
procedure TForm1.Button1Click(Sender: TObject);
var
  i: Integer;
begin
  ListBox1.Clear;
  ListBox1.Items[0]:= 'Destination Airports:';
  with Flights do
  begin
    DisableControls;
    try
      First;
      i:= 1;
      ListBox1.Items[0]:= 'Destination Airports:';
      while not Eof do
      begin
        ListBox1.Items[i]:= Fields[2].Value;;
        i:= i + 1;
        Next;
      end;
    finally
      EnableControls;
    end;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
var
  i: Integer;
begin
  Flights:= TTable.Create(Form1);
  with Flights do
  begin
    TableName := 'Flights';
    // This path depends on the Demos directory of your RAD Studio installation.
    DatabaseName :=
      'c:\Documents and Settings\All Users\Documents\RAD Studio\6.0\Demos\IntraWeb\Win32\FlightInformation\Data';

  end;
  DS2.DataSet:= Flights;
  DBGrid2.DataSource.DataSet:= Flights;
  Flights.Active:= True;
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;