MongoDB with UniDAC in Delphi

//UniConnection1.SpecificOptions.Values['MongoDB.BSONLibrary'] :=
//    'C:\...\libbson-1.0.dll';
//UniConnection1.SpecificOptions.Values['MongoDB.ClientLibrary'] :=
//    'C:\...\libmongoc-1.0.dll';
//UniQuery1 : Data Type Mapping : string(Database Type) - WideString(Field Type)
//UniQuery1 : Data Type Mapping : null(Database Type) - String(Field Type)

procedure TForm1.Button1Click(Sender: TObject);
var
  doc: TMongoDocument; // uses MongoObjectsUni
begin
  try
    UniQuery1.Close;
    UniQuery1.SQL.Clear;
    UniQuery1.SQL.Text := 
        '{"find":"TestCollection", "filter":{"age":{"$gte": 31}}}';
    UniQuery1.Open;
    while not UniQuery1.Eof do
    begin
      doc := UniQuery1.GetObject('TestCollection') as TMongoDocument;
      Memo1.Lines.Add(doc.FieldByName['name'].GetData.AsString + ' / ' 
          + doc.FieldByName['age'].GetData.AsString);
      UniQuery1.Next;
    end;
  except
    on E: Exception do
      Memo1.Text := E.Message;
  end;
end;