Ich kann meine Monat, Tag, Jahr Dropdown-Listen nicht von meinem ASP.NET MVC3 ViewModel

Question

Ich konvertiere über zu MVC 3 von Webforms und hatte einige Schwierigkeiten bei der Lehre selbst. Ich habe ein ViewModel erstellt, das drei separate Auswahllisten mit den Werten für Monat, Tag und Jahr in meinem _Header füllen sollte. Ich denke, ich habe ein Strukturproblem. Das Endergebnis ist, dass ich eine unbehandelte Ausnahme im WWW-Dienst auf meinem Computer verursache und Visual Studio erscheint und möchte, dass ich es debugge. Jede Hilfe würde sehr geschätzt werden!

Hier ist mein Code.

DateSearchViewModel.cs

namespace DH.ViewModels 
{ 
    public class DateSearchViewModel 
    { 
     //MONTH DROPDOWN LIST 
     public class MonthViewModel 
     { 
      public int ID { set; get; } 
      public string Month { set; get; } 
     }  

     private List<MonthViewModel> _months; 
     public List<MonthViewModel> Months 
     { 
      get 
      { 
       if (_months == null) 
       { 
        _months = new List<MonthViewModel>(); 
        _months.Add(new MonthViewModel { ID = 1, Month = "Jan" }); 
        _months.Add(new MonthViewModel { ID = 2, Month = "Feb" }); 
        _months.Add(new MonthViewModel { ID = 3, Month = "Mar" }); 
        _months.Add(new MonthViewModel { ID = 4, Month = "Apr" }); 
        _months.Add(new MonthViewModel { ID = 5, Month = "May" }); 
        _months.Add(new MonthViewModel { ID = 6, Month = "Jun" }); 
        _months.Add(new MonthViewModel { ID = 7, Month = "Jul" }); 
        _months.Add(new MonthViewModel { ID = 8, Month = "Aug" }); 
        _months.Add(new MonthViewModel { ID = 9, Month = "Sep" }); 
        _months.Add(new MonthViewModel { ID = 10, Month = "Oct" }); 
        _months.Add(new MonthViewModel { ID = 11, Month = "Nov" }); 
        _months.Add(new MonthViewModel { ID = 12, Month = "Dec" }); 
       } 
       return _months; 
      } 
     } 
     public int SelectedMonthID { set; get; } 


     //DAY DROPDOWN LIST 
     public class DayViewModel 
     { 
      public int ID { set; get; } 
      public string Day { set; get; } 
     } 
     private List<DayViewModel> _days; 
     public List<DayViewModel> Days 
     { 
      get 
      { 
       if (_days == null) 
       { 
        _days = new List<DayViewModel>(); 
        _days.Add(new DayViewModel { ID = 1, Day = "1" }); 
        _days.Add(new DayViewModel { ID = 2, Day = "2" }); 
        _days.Add(new DayViewModel { ID = 3, Day = "3" }); 
        _days.Add(new DayViewModel { ID = 4, Day = "4" }); 
        _days.Add(new DayViewModel { ID = 5, Day = "5" }); 
        _days.Add(new DayViewModel { ID = 6, Day = "6" }); 
        _days.Add(new DayViewModel { ID = 7, Day = "7" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "8" }); 
        _days.Add(new DayViewModel { ID = 9, Day = "9" }); 
        _days.Add(new DayViewModel { ID = 10, Day = "10" }); 
        _days.Add(new DayViewModel { ID = 11, Day = "11" }); 
        _days.Add(new DayViewModel { ID = 12, Day = "12" }); 
        _days.Add(new DayViewModel { ID = 1, Day = "13" }); 
        _days.Add(new DayViewModel { ID = 2, Day = "14" }); 
        _days.Add(new DayViewModel { ID = 3, Day = "15" }); 
        _days.Add(new DayViewModel { ID = 4, Day = "16" }); 
        _days.Add(new DayViewModel { ID = 5, Day = "17" }); 
        _days.Add(new DayViewModel { ID = 6, Day = "18" }); 
        _days.Add(new DayViewModel { ID = 7, Day = "19" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "20" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "21" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "22" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "23" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "24" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "25" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "26" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "27" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "28" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "29" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "30" }); 
        _days.Add(new DayViewModel { ID = 8, Day = "31" }); 
       } 
       return _days; 
      } 
     } 
     public int SelectedDayID { set; get; } 


     //YEAR DROPDOWN LIST 
     public class YearViewModel 
     { 
      public int ID { set; get; } 
      public string Year { set; get; } 
     } 
     private List<YearViewModel> _years; 
     public List<YearViewModel> Years 
     { 
      get 
      { 
       if (_years == null) 
       { 
        _years = new List<YearViewModel>(); 
        _years.Add(new YearViewModel { ID = 1, Year = "2009" }); 
        _years.Add(new YearViewModel { ID = 2, Year = "2010" }); 
        _years.Add(new YearViewModel { ID = 3, Year = "2011" }); 
        _years.Add(new YearViewModel { ID = 4, Year = "2012" }); 
       } 
       return _years; 
      } 
     }  
     public int SelectedYearID { set; get; } 
    } 
} 

CommonController.cs:

[ChildActionOnly] 
public ActionResult _Header() 
{ 
    DateSearchViewModel DateVM = new DateSearchViewModel(); 
    return View(DateVM); 
} 

_Header.cshtml:

@model DH.ViewModels.DateSearchViewModel 

@Html.DropDownListFor(x => x.SelectedMonthID, new SelectList(Model.Months, "ID", "Month"), "--Select--") 
@Html.DropDownListFor(x => x.SelectedDayID, new SelectList(Model.Days, "ID", "Day"), "--Select--") 
@Html.DropDownListFor(x => x.SelectedYearID, new SelectList(Model.Years, "ID", "Year"), "--Select--") 

_Layout.cshtml:

@{Html.RenderAction("_Header", "Common");} 

Answer 1

Ich habe das Gefühl, dass dein Modell zu kompliziert ist ... ein Modell für den Tag und das Jahr der Motte zu haben, erscheint mir als Overkill. Ich würde diese nur als Eigenschaften implementieren. Hier ist, wie ich dies erreichen würde:

Das Modell:

public class DateSearchViewModel { 
    public int Day { get; set; } 
    public int Month { get; set; } 
    public int Year { get; set; } 
} 

Der Controller:

public ActionResult _Header() { 
    DateSearchViewModel DateVM = new DateSearchViewModel(); 
    return View(DateVM); 
} 
public ActionResult _Header(DateSearchViewModel vm) { 
    if(ModelState.IsValid) { 
    // save vm to database, etc. 
    } 
    return View(vm); 
} 

Und die Aussicht:

@{ 
    var days = new List<SelectListItem>(); 
    for(var i = 1; i <= 31; i++) { 
    days.Add(new SelectListItem { Text = i.ToString(), Value = i.ToString(), Selected = Model.Day == i }); 
    } 
    var months = new List<SelectListItem> { 
    new SelectListItem {Text = "Jan", Value = "1", Selected = Model.Month == 1}, 
    new SelectListItem {Text = "Feb", Value = "2", Selected = Model.Month == 2}, 
    new SelectListItem {Text = "Mar", Value = "3", Selected = Model.Month == 3}, 
    new SelectListItem {Text = "Apr", Value = "4", Selected = Model.Month == 4}, 
    new SelectListItem {Text = "May", Value = "5", Selected = Model.Month == 5}, 
    new SelectListItem {Text = "Jun", Value = "6", Selected = Model.Month == 6}, 
    new SelectListItem {Text = "Jul", Value = "7", Selected = Model.Month == 7}, 
    new SelectListItem {Text = "Aug", Value = "8", Selected = Model.Month == 8}, 
    new SelectListItem {Text = "Sep", Value = "9", Selected = Model.Month == 9}, 
    new SelectListItem {Text = "Oct", Value = "10", Selected = Model.Month == 10}, 
    new SelectListItem {Text = "Nov", Value = "11", Selected = Model.Month == 11}, 
    new SelectListItem {Text = "Dec", Value = "12", Selected = Model.Month == 12}, 
    }; 
    var years = new List<SelectListItem>(); 
    for(var i = 2009; i <= 2012; i++) { 
    years.Add(new SelectListItem { Text = i.ToString(), Value = i.ToString(), Selected = Model.Year == i }); 
    } 
} 
@using(Html.BeginForm()) { 
    @Html.DropDownListFor(x => x.Month, months) 
    @Html.DropDownListFor(x => x.Day, days) 
    @Html.DropDownListFor(x => x.Year, years) 
    <input type="submit" /> 
}