public static string GetSearchVacantRecord(string columnname, ICollection <QueryCondition> lstCondition, ICollection <QueryCondition> vacantCond) { try { QueryDesigner objQuery = new QueryDesigner(); return(JsonConvert.SerializeObject(objQuery.GetDynamicVacantRecord(lstCondition, columnname, vacantCond))); } catch (Exception ex) { return(null); } }