How to modify the DatabaseName stored with a DADE Query

Currently when DADE is used to create dataviews, the DatabaseName is stored as part of the query definition. (This is consistent with Delphi’s approach to specifying a database connection for a Query object).

In some cases, you may decide that the DatabaseName needs to be modified at a later date.

We recommend that the DatabaseName refer to a TDatabase connection component or to an Alias to provide flexibility for changing the connection parameters.

A second way to handle this issue is to implement some code that specifies a DatabaseName whenever a template is loaded. This can be accomplished by using the Report.Template.OnLoadEnd event.

1. Declare an event-handler procedure in the private section of your form declaration.

   type
      myForm = class(TForm)
        private
          procedure ReportTemplateLoadEndEvent(Sender: TObject);
        public
      end;

    

2. Use the FormCreate event to assign the event-handler to the event property.

   procedure myForm.FormCreate(Sender: TObject)
   begin
     Report1.Template.OnLoadEnd := ReportTemplateLoadEndEvent;
   
   end;

    

3. Add code to the event-handler to specify the database name.

   procedure myForm.ReportTemplateLoadEndEvent(Sender: TObject)
   var
     lSQL: TdaSQL;
   
   begin
     if GetSQLObject(Report1, lSQL) then
       begin
         lSQL.DatabaseName := Designer.DataSettings.DatabaseName;
         SetSQLObject(Report, lSQL);
         lSQL.Free;
   
       end;
   
   end;

    

Below is a tech tip for extracting the SQL object from a report. TdaSQL is a class defined in daSQL.pas.
The example code extracts only DataViews[0]. If the report contains multiple dataviews, you will need to iterate thru all of the entries in the DataViews[] array.

uses
  daDatMod;

function GetSQLObject(aReport: TppReport; var aSQL: TdaSQL): Boolean;
var
  lDataModule: TdaDataModule;
  lDataView: TdaDataView;
begin

  aSQL := TdaSQL.Create(nil);

  {get the datamodule}
  lDataModule := daGetDataModule(aReport);

  if (lDataModule <> nil) then
    begin
      lDataView := lDataModule.DataViews[0];

      if (lDataView <> nil) and (lDataView is TdaQueryDataView) then
        aSQL.Assign(TdaQueryDataView(lDataView).SQL);

    end;

  Result := (aSQL <> nil);

end;

procedure SetSQLObject(aReport: TppReport; aSQL: TdaSQL);
var
  lDataModule: TdaDataModule;
  lDataView: TdaDataView;
begin

  {get the datamodule}
  lDataModule := daGetDataModule(aReport);

  if (lDataModule <> nil) then
    begin
      lDataView := lDataModule.DataViews[0];

      if (lDataView <> nil) and (lDataView is TdaQueryDataView) then
        TdaQueryDataView(lDataView).SQL := aSQL;

    end;

end;