/// <summary>
        /// Initializes a new instance of the <see cref="PatientListViewModel"/> class.
        /// </summary>
        /// <param name="userDialogService">The user dialog service.</param>
        /// <param name="asyncRequestDispatcherFactory">The async request dispatcher factory.</param>
        /// <param name="accessControlManager">The access control manager.</param>
        /// <param name="commandFactory">The command factory.</param>
        public PatientListViewModel(
            IUserDialogService userDialogService,
            IAsyncRequestDispatcherFactory asyncRequestDispatcherFactory,
            IAccessControlManager accessControlManager,
            ICommandFactory commandFactory )
            : base(accessControlManager, commandFactory)
        {
            _userDialogService = userDialogService;
            _asyncRequestDispatcherFactory = asyncRequestDispatcherFactory;

            var commandFactoryHelper = CommandFactoryHelper.CreateHelper ( this, commandFactory );

            SearchCommand = commandFactoryHelper.BuildDelegateCommand ( () => SearchCommand, ExecuteSearchCommand );
            ClearCommand = commandFactoryHelper.BuildDelegateCommand ( () => ClearCommand, ExecuteClearCommand );

            PatientListCriteria = new PatientListCriteriaDto ();
            PatientListCriteria.PageSize = DEFAULTPAGESIZE;
            PatientListCriteria.LabResultFilterModifier = FilterModifier.EqualTo;
            PatientListCriteria.AgeFilterModifier = FilterModifier.EqualTo;

            FilterModifierList = new List<string>
                {
                    FilterModifier.EqualTo,
                    FilterModifier.GreaterThan,
                    FilterModifier.GreaterThanOrEqualTo,
                    FilterModifier.LessThen,
                    FilterModifier.LessThenOrEqualTo
                };
        }
 private void ExecuteClearCommand()
 {
     var oldSize = PatientListCriteria.PageSize;
     PatientListCriteria = new PatientListCriteriaDto
         {
             PageSize = oldSize,
             LabResultFilterModifier = FilterModifier.EqualTo,
             AgeFilterModifier = FilterModifier.EqualTo
         };
 }