MVC3 - passing null item when model requires TimeSpan - asp.net-mvc-3

Question

Well I've recently come up against an interesting problem that I can't seem to figure out.
The error message I get is:
{"The model item passed into the dictionary is null, but this dictionary requires a non-null model item of type 'System.TimeSpan'."}
This occurs when I try to submit a new entry to the database. So, the details of what is being submitted.
The model class:
public class EventModel
{
[Key]
public int EventID { get; set; }
[DisplayName("Booking title")]
[Required(ErrorMessage="Please provide a title for the booking")]
public string Title { get; set; }
[DataType(DataType.Date)]
[DisplayName("Start date")]
[DisplayFormat(DataFormatString="{0:dd/MM/yyyy}", ApplyFormatInEditMode = true)]
public DateTime StartDateTime { get; set; }
[DisplayName("End date")]
[DataType(DataType.Date)]
[DisplayFormat(DataFormatString = "{0:dd/MM/yyyy}", ApplyFormatInEditMode = true)]
[IsDateAfter("StartDateTime", true, ErrorMessage="End date must be on or after the start date")]
public DateTime EndDateTime { get; set; }
public long StartTicks { get; set; }
public long EndTicks { get; set; }
[NotMapped]
[DisplayName("Start Time")]
public TimeSpan StartTime
{
get { return TimeSpan.FromTicks(StartTicks); }
set { StartTicks = value.Ticks; }
}
[NotMapped]
[DisplayName("End Time")]
public TimeSpan EndTime
{
get { return TimeSpan.FromTicks(EndTicks); }
set { EndTicks = value.Ticks; }
}
[DefaultValue(2)]
[DisplayName("Booking is")]
public int BookingStatus { get; set; }
[DisplayName("Set recurrence")]
[DefaultValue(false)]
public bool DoesRecur { get; set; }
[DisplayName("Set recurrence type")]
public string Pattern { get; set; }
[DisplayName("Set the day this happens on ")]
public int DayIndex { get; set; }
[DisplayName("Choose the day instance this recurs on")]
public int DayCount { get; set; }
[DisplayName("Day ")]
[NotMapped]
public string Day { get; set; }
[DisplayName("Instance")]
[NotMapped]
public string Instance { get; set; }
// links resource to a user/member
[DisplayName("Booked by")]
[NotMapped]
public string BookerName { get; set; }
public Guid MemberID { get; set; }
// links resource to a resource type
[DisplayName("Resource required:")]
public int ResourceID { get; set; }
}
The action methods in the controller class:
[HttpGet]
public ActionResult Create(DateTime eventDate)
{
var days = from DayOfWeek d in Enum.GetValues(typeof(DayOfWeek))
select new { ID = (int) d, Name = (DayOfWeek)d };
var instance = from DayInstance i in Enum.GetValues(typeof(DayInstance))
select new { ID = (int) i, Name = (DayInstance)i };
MembershipUser mu = Membership.GetUser(HttpContext.Profile.UserName);
CreateEventViewModel model = new CreateEventViewModel()
{
Event = new EventModel()
{
StartDateTime = eventDate,
EndDateTime = eventDate,
MemberID = (Guid)mu.ProviderUserKey
},
Resources = DBContext.Resources.ToList(),
Patterns = DBContext.Patterns.ToList(),
ResourceTypes = DBContext.ResourceTypes.ToList()
};
ViewData["dayOfWeek"] = new SelectList(days, "ID", "Name", DayOfWeek.Monday);
ViewData["dayInstance"] = new SelectList(instance, "ID", "Name", DayInstance.First);
return View(model);
}
[HttpPost]
public ActionResult Create(CreateEventViewModel em)
{
if (ModelState.IsValid)
{
// get the resource turn aournd time
double turnAround = rc.GetResourceTurnAround(em.Event.ResourceID);
MembershipUser mu = Membership.GetUser(HttpContext.Profile.UserName);
em.Event.MemberID = (Guid) mu.ProviderUserKey;
em.Event.BookingStatus = 2;
// need to get the time added to the date.
DateTime actualStartPoint = new DateTime(em.Event.StartDateTime.Ticks + em.Event.StartTicks);
DateTime actualEndPoint = new DateTime(em.Event.EndDateTime.Ticks + em.Event.EndTicks);
em.Event.StartDateTime = actualStartPoint;
em.Event.EndDateTime = actualEndPoint;
// add turn around time to the end of the event
em.Event.EndDateTime = em.Event.EndDateTime.AddMinutes(turnAround);
// needed becase these are handled slighty differently to the rest of the model
em.Event.DayIndex = int.Parse(Request.Form.GetValues("dayOfWeek").GetValue(0).ToString());
em.Event.DayCount = int.Parse(Request.Form.GetValues("dayInstance").GetValue(0).ToString());
DBContext.Events.Add(em.Event);
DBContext.SaveChanges();
// get the resource owner
MembershipUser resourceOwner = Membership.GetUser(rc.GetResourceOwnerByID(em.Event.ResourceID));
// email the admin team and the user the details of this booking
// get the email address of the user making the booking
StringBuilder message = new StringBuilder();
message.AppendFormat("Thank you for your booking, this is now being reviewed by the team.\nThe details of your booking are included for confirmation.\n");
message.AppendFormat("Booking Title: {0}\nResource: {1}\n Date: {2} {3} (this includes our turn around time added on)\n", em.Event.Title, rc.GetResourceNameByID(em.Event.ResourceID), actualStartPoint, actualEndPoint);
message.AppendFormat("You can log in at any time to review your bookings.\nYou will receive an email when the team have reviewed this request\nMany thanks\n");
EmailHandler eh = new EmailHandler();
eh.SetRecipient(Membership.GetUser().Email);
eh.AddAdminEmail();
eh.AddBcc(resourceOwner.Email);
eh.SetSubject("Booking Requested");
eh.SetBody(message.ToString());
eh.sendMessage();
return RedirectToAction("Index");
}
else
{
return View();
}
}
Now for the view items - the main view:
#model AssetManager.Models.CreateEventViewModel
#{
ViewBag.Title = "Create";
Layout = "~/Views/Shared/_Layout.cshtml";
}
#using (Html.BeginForm())
{
#Html.ValidationSummary(true)
<fieldset>
<legend id="bookingLegend">Place Booking</legend>
<div class="controlcontainer">
<div class="editor-label">
#Html.LabelFor(model => model.Event.Title)
</div>
<div class="editor-field">
#Html.EditorFor(model => model.Event.Title)
#Html.ValidationMessageFor(model => model.Event.Title)
</div>
</div>
<div class="controlcontainer">
<div class="editor-label">
#Html.LabelFor(model => model.Event.StartDateTime)
</div>
<div class="editor-field">
#Html.EditorFor(model => model.Event.StartDateTime, new { #class = "date" })
#Html.ValidationMessageFor(model => model.Event.StartDateTime)
</div>
</div>
<div class="controlcontainer">
<div class="editor-label timeSelector">
#Html.LabelFor(model => model.Event.StartTime)
</div>
<div class="editor-field timeSelector">
#Html.EditorFor(model => model.Event.StartTime)
#Html.ValidationMessageFor(model => model.Event.StartTime)
</div>
</div>
<div class="controlcontainer">
<div class="editor-label">
#Html.LabelFor(model => model.Event.EndDateTime)
</div>
<div class="editor-field">
#Html.EditorFor(model => model.Event.EndDateTime, new { #class = "date" })
#Html.ValidationMessageFor(model => model.Event.EndDateTime)
</div>
</div>
<div class="controlcontainer">
<div class="editor-label timeSelector">
#Html.LabelFor(model => model.Event.EndTime)
</div>
<div class="editor-field timeSelector">
#Html.EditorFor(model => model.Event.EndTime)
#Html.ValidationMessageFor(model => model.Event.EndTime)
</div>
</div>
<div class="controlcontainer">
<div class="editor-label">
#Html.Label("Select Resource Type")
</div>
<div class="editor-field">
#Html.DropDownList("ResourceTypes", new SelectList(Model.ResourceTypes, "ResourceTypeID", "Title"), "-- Select Resource Type --", new { #id = "ddlResourceTypes" })
</div>
</div>
<div class="controlcontainer">
<div class="editor-label">
#Html.LabelFor(model => model.Event.ResourceID)
</div>
<div class="editor-field">
#Html.DropDownListFor(model => model.Event.ResourceID, new SelectList(Enumerable.Empty<SelectListItem>(), "ResourceType", "Name"), "-- Select Resource --", new { #id = "ddlResources" })
#Html.ValidationMessageFor(model => model.Event.ResourceID)
</div>
</div>
<div class="controlcontainer">
<div class="editor-label">
#Html.LabelFor(model => model.Event.DoesRecur)
</div>
<div class="editor-field">
#Html.EditorFor(model => model.Event.DoesRecur)
#Html.ValidationMessageFor(model => model.Event.DoesRecur)
</div>
</div>
<div id="recurType" class="controlcontainer">
<div class="editor-label">
#Html.LabelFor(model => model.Event.Pattern)
</div>
<div class="editor-field">
#Html.DropDownListFor(model => model.Event.Pattern, new SelectList(Model.Patterns, "PatternCode", "Pattern"), "-- Select Recurrence Pattern --")
#Html.ValidationMessageFor(model => model.Event.Pattern)
</div>
</div>
<div id="recurDayHappens" class="controlcontainer">
<div class="editor-label">
#Html.LabelFor(model => model.Event.DayIndex)
</div>
<div class="editor-field">
#Html.DropDownList("dayOfWeek")
#Html.ValidationMessageFor(model => model.Event.DayIndex)
</div>
</div>
<div id="recurInstance" class="controlcontainer">
<div class="editor-label">
#Html.LabelFor(model => model.Event.DayCount)
</div>
<div class="editor-field">
#Html.DropDownList("dayInstance")
#Html.ValidationMessageFor(model => model.Event.DayCount)
</div>
</div>
<div class="controlcontainer">
<p>
<input class="subButton" type="submit" value="Create" />
<input id="cancelBtn" class="cancelButton" type="button" value="Cancel" onclick="location.href='#Url.Action("Index", "Calendar")'" />
</p>
</div>
</fieldset>
}
Then there is an editor template for the TimeSpan items:
#model TimeSpan
#Html.DropDownList("Hours", Enumerable.Range(0, 24)
.Select(i => new SelectListItem { Value = i.ToString(),
Text = i.ToString(), Selected = Model.Hours == i })) :
#Html.DropDownList("Minutes", Enumerable.Range(0, 60)
.Select(i => new SelectListItem { Value = i.ToString(),
Text = i.ToString(), Selected = Model.Minutes == i }))
And finally a TimeBinder class:
public class TimeBinder : IModelBinder
{
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
// Ensure there's incomming data
var key_hours = bindingContext.ModelName + ".Hours";
var valueProviderResult_hours = bindingContext.ValueProvider
.GetValue(key_hours);
var key_minutes = bindingContext.ModelName + ".Minutes";
var valueProviderResult_minutes = bindingContext.ValueProvider
.GetValue(key_minutes);
if (valueProviderResult_hours == null || string.IsNullOrEmpty(valueProviderResult_hours.AttemptedValue)
|| valueProviderResult_minutes == null || string.IsNullOrEmpty(valueProviderResult_minutes.AttemptedValue))
{
return null;
}
// Preserve it in case we need to redisplay the form
bindingContext.ModelState.SetModelValue(key_hours, valueProviderResult_hours);
bindingContext.ModelState.SetModelValue(key_minutes, valueProviderResult_minutes);
// Parse
var hours = ((string[])valueProviderResult_hours.RawValue)[0];
var minutes = ((string[])valueProviderResult_minutes.RawValue)[0];
// A TimeSpan represents the time elapsed since midnight
var time = new TimeSpan(Convert.ToInt32(hours), Convert.ToInt32(minutes), 0);
return time;
}
}
That's it, that is all the code that is involved. I am completely baffled as to why this error occurs. Any ideas or suggestions as to the cause and the solution are greatly appreciated.
Many thanks
nathj07
EDIT
Pk, so I tried something differnt with th TimeSpan editor template:
#model TimeSpan?
#Html.DropDownList("Hours", Enumerable.Range(0, 24)
.Select(i => new SelectListItem
{
Value = i.ToString(),
Text = i.ToString(),
Selected = Model.HasValue ? Model.Value.Hours == i : false
})) :
#Html.DropDownList("Minutes", Enumerable.Range(0, 60)
.Select(i => new SelectListItem
{
Value = i.ToString(),
Text = i.ToString(),
Selected = Model.HasValue ? Model.Value.Minutes == i : false
}))
This seems to have overcome this error but now I get an issue a little further down. In the view there is a DropDownList("ResourceTypes"....) This is essentially a dropdownlist that is used to control what appears in the DropDownListFor(model=>model.Event.ResourceID.....) There is a simple piece of JavaScript:
$(document).ready(function () {
$("#ddlResourceTypes").change(function () {
var idResourceType = $('#ddlResourceTypes').val();
$.getJSON("/Resource/LoadResourcesByType", { id: idResourceType },
function (resourceData) {
var select = $("#ddlResources");
select.empty();
select.append($('<option/>', {
value: 0,
text: "-- Select Resource --"
}));
$.each(resourceData, function (index, itemData) {
select.append($('<option/>', {
value: itemData.Value,
text: itemData.Text
}));
});
});
});
});
Now the issue I get is:
Object reference not set to an instance of an object
On the DropDownList("ResourceTypes".....)
Any ideas on this one?

Answer 1

When you POST an invalid form, you end with the code return View().
So you display the same view, without passing a model, the Model will be null. The first time your code really needs a value is in the editor for TimeSpan. That value is a nullable now, but you never test for the case that it is null.
Change the return to:
return View(em);
to pass the model, or use the code from the GET action, to rebuild and pass the model:
return Create(/* Your create date */);
Edit after comment
The error in the ModelBinder might be caused by the lines:
var hours = ((string[])valueProviderResult_hours.RawValue)[0];
var minutes = ((string[])valueProviderResult_minutes.RawValue)[0];
You convert an array to a string[]. I would do the conversion to string as late as possible, and make it more error proof by:
var hours = Convert.ToString(((object[])valueProviderResult_hours.RawValue).FirstOrDefault()) ?? "00";
This will just cast to an array of object, so there's less change to fail. Take the first element, or return null, and convert that to a string using Convert, and if the result is still null, return "00".

Answer 2

Hit breakpoints in your partial views and check the Model object, somewhere you will find a wrong object for a partial view. that is the cause of this error