Getting Criteria from ListGrid

[tape6]

Hi,

I'm working on information system baset on SmartGWT, we are using server side filtering with getting criteria on client side. Problem appears when grid conatins field with type ListGridFieldType.DATE then a get
{operator=and, _constructor=AdvancedCriteria, criteria=[object Object]}
instead of filter data. Is there any solution how to get criteria in this case?

public void filterGrid() {
		userGridCriteria = getFilterEditorCriteria();

		String valueString;
		//Date valueDate;
		String nonValidCriteria = "";
		filterOfGrid.clearList();

		for (int i = 0; i < fields.length; i++) {
			if (userGridCriteria.getValues() != null && userGridCriteria.getValues().get(fields[i].getName()) != null) {
				firstRow = 0;
				FilterVo filterVo = null;

				if (fields[i].getType() == ListGridFieldType.INTEGER) {
                                      .........

thx