Question
“How can I add search criteria that will be not be visible to my end-users?”
Solution
The following example shows how to use the DataView.OnBeforeGenerateSQL and OnAfterGenerateSQL events to and remove search criteria that cannot be seen by the end-user.
Download: DADEInvisibleSearchCriteria.zip
Delphi code sample:
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procedure TForm1.Button1Click(Sender: TObject); begin PrepareReport(ppReport1); ppReport1.Print; end; procedure TForm1.PrepareReport(aReport: TppCustomReport); var lDataView: TdaQueryDataView; begin lDataView := GetDataViewForReport(aReport); // add event-handlers for the before/after generate SQL events if (lDataView <> nil) then begin lDataView.OnBeforeGenerateSQL := ehDataView_BeforeGenerateSQL; lDataView.OnAfterGenerateSQL := ehDataView_AfterGenerateSQL; end; end; function TForm1.GetDataViewForReport(aReport: TppCustomReport): TdaQueryDataView; begin if aReport.DataPipeline = nil then Result := nil else if not(aReport.DataPipeline.DataView is TdaQueryDataView) then Result := nil else Result := TdaQueryDataView(aReport.DataPipeline.DataView); end; procedure TForm1.ehDataView_BeforeGenerateSQL(Sender: TObject; aSQL: TdaSQL); var lSQLBuilder: TdaSQLBuilder; begin // use SQLBuilder to add search criteria lSQLBuilder := TdaSQLBuilder.Create(aSQL); lSQLBuilder.SearchCriteria.Add('Customer', 'Company', 'Like', 'A'); lSQLBuilder.Free; end; procedure TForm1.ehDataView_AfterGenerateSQL(Sender: TObject; aSQL: TdaSQL); var lSQLBuilder: TdaSQLBuilder; begin // use SQLBuilder to remove search criteria lSQLBuilder := TdaSQLBuilder.Create(aSQL); lSQLBuilder.SearchCriteria.Remove('Customer', 'Company'); lSQLBuilder.Free; end; |