Build new sample - DataModule

[bogdanpolak]

Use code snippets to build new sample project: 03-datamodule

procedure TDataModule1.OnCreate(Sender: TObject);
begin
  fOrdersProxy := TOrdersProxy.Create(fOwner);
  fOrdersDataSource := fOrdersProxy.ConstructDataSource;
end;

procedure TDataModule1.InitOrders(aYear, aMonth: word);
begin
  fOrdersProxy.WithFiredacSQL( FDConnection1,
    'SELECT OrderID, CustomerID, OrderDate, Freight' +
    ' FROM {id Orders} WHERE OrderDate between' +
    ' :StartDate and :EndDate', 
    [ GetMonthStart(aYear, aMonth), 
      GetMonthEnd(aYear, aMonth) ],
    [ftDate, ftDate])
    .Open;
  fOrdersInitialized := True;
end;

procedure TDataModule1.InitOrders(aDataSet: TDataSet);
begin
  fOrdersProxy.WithDataSet(aDataSet).Open;
  fOrdersInitialized := True;
end;

function TDataModule.CalculateTotalOrders (const aCustomerID: string): Currency;
begin
  Result := 0;
  procedure ForEach(OnElem: TProc);
  fOrdersProxy.ForEach(procedure
    begin
      if fOrdersProxy.CustomerID.Value = aCustomerID then
        Result := Result + fOrdersProxy.GetTotalOrderValue;
    end;
end;