FetchParams (Delphi)

Description

This example uses the FetchParams method to sync the params with the server.

Code

procedure TForm1.SaveParamsClick(Sender: TObject);
begin
  { Save the parameters for the TDataSet. }
  SavedParams.Assign(CDS.Params);
end;

procedure TForm1.AlterParamsClick(Sender: TObject);
var
  I : Integer;
  ListItem: string;
begin
  CDS.Params.CreateParam(ftString, 'stringParam', ptInput);  // you can also edit the params in the CDS dynamically
  CDS.Params.CreateParam(ftSmallInt, 'smallIntParam', ptInput);
  CDS.Params.CreateParam(ftInteger, 'intParam', ptInput);
  CDS.Params.CreateParam(ftWord, 'wordParam', ptInput);
  CDS.Params.CreateParam(ftBoolean, 'boolParam', ptInput);
  CDS.Params.CreateParam(ftFloat, 'floatParam', ptInput);
  CDS.Params.CreateParam(ftCurrency, 'currencyParam', ptInput);
  CDS.Params.CreateParam(ftBCD, 'bcdParam', ptInput);
  CDS.Params.CreateParam(ftDate, 'dateParam', ptInput);
  CDS.Params.CreateParam(ftTime, 'timeParam', ptInput);
  CDS.Params.CreateParam(ftDateTime, 'dateTimeParam', ptInput);
  { Call FetchParams to ensure that parameters reflect server metadata. }
  CDS.FetchParams;
  with CDS.Params do
  begin
    for I := 0 to Count - 1 do
    begin
      ListItem := ListBox1.Items[I];
      case Items[I].DataType of
        ftString:
          Items[I].AsString := ListItem;
        ftSmallInt:
          Items[I].AsSmallInt := StrToIntDef(ListItem, 0);
        ftInteger:
          Items[I].AsInteger := StrToIntDef(ListItem, 0);
        ftWord:
          Items[I].AsWord := StrToIntDef(ListItem, 0);
        ftBoolean:
          begin
            if ListItem = 'True' then
              Items[I].AsBoolean := True
            else
              Items[I].AsBoolean := False;
          end;
        ftFloat:
          Items[I].AsFloat := StrToFloat(ListItem);
        ftCurrency:
          Items[I].AsCurrency := StrToFloat(ListItem);
        ftBCD:
          Items[I].AsBCD := StrToCurr(ListItem);
        ftDate:
          Items[I].AsDate := StrToDate(ListItem);
        ftTime:
          Items[I].AsTime := StrToTime(ListItem);
        ftDateTime:
          Items[I].AsDateTime := StrToDateTime(ListItem);
      end;
    end;
  end;
end;

procedure TForm1.RestoreParamsClick(Sender: TObject);
begin
  { Restore the parameters to TDataSet. }
  CDS.Params.AssignValues(SavedParams);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  { Initialize SavedParams. }
  SavedParams := TParams.Create;
  ListBox1.Items.Add('Here is a string');
  ListBox1.Items.Add('4');
  ListBox1.Items.Add('3456789');
  ListBox1.Items.Add('34');
  ListBox1.Items.Add('0');
  ListBox1.Items.Add('12.56');
  ListBox1.Items.Add('4.23');
  ListBox1.Items.Add('99.5');
  ListBox1.Items.Add('4/12/53');
  ListBox1.Items.Add('7:45:00');
  ListBox1.Items.Add('4/12/53 7:45:00');
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  SavedParams.Free;
end;

Uses

• Datasnap.DBClient.TCustomClientDataSet.FetchParams ( fr | de | ja )
• Datasnap.DBClient.TCustomClientDataSet.Params ( fr | de | ja )
• Data.DB.TParam.DataType ( fr | de | ja )
• Data.DB.TParams.Items ( fr | de | ja )
• System.SysUtils.StrToIntDef ( fr | de | ja )