Model Binding Error for Parent Object Entity - asp.net-core

Question

Using latest ASP.NET Core, Windows 10 Pro
TLDR: my controller is returning a "Microsoft.AspNetCore.Mvc.ModelBinding.ModelError" for an entity's parent.
Entity: Schedule
public class Schedule
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ScheduleId { get; set; }
[Required]
[Display(Name = "Start On")]
public DateTime StartDateTime { get; set; } = DateTime.Now.AddMinutes(1);
[Display(Name = "Reschedule On")]
public string Recurrence { get; set; }
[Display(Name = "Parameter 1")]
[MaxLength(256), StringLength(256)]
public string Param1 { get; set; }
// ... more properties
[Display(Name = "Parameter 7")]
[MaxLength(256), StringLength(256)]
public string Param7 { get; set; }
[Display(Name = "Message Text")]
public string MessageText { get; set; }
#region relationships
[Required]
[Display(Name = "For Process")]
public int ProcessId { get; set; }
[Required]
[Display(Name = "For Process")]
public virtual Process Process { get; set; }
public virtual ICollection<ScheduleNotification> ScheduleNotifications { get; set; }
#endregion
}
Entity: Process
public class Process : IValidatableObject
{
private int? _ApplicationId;
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Key]
public int ProcessId { get; set; }
[Required]
[StringLength(80, MinimumLength = 5, ErrorMessage = "Names must be between 5 and 80 characters")]
[MaxLength(80)]
public string Name { get; set; }
public string Description { get; set; }
[Required]
[Display(Name = "Process Type")]
public ProcessTypeEnum ProcessType { get; set; }
// ... more properties
[Display(Name = "Primary Application")]
public int? ApplicationId
{
get
{
return _ApplicationId;
}
set
{
_ApplicationId = value == 0 ? null : value;
}
}
public Application Application { get; set; }
public ICollection<Schedule> Schedules { get; set; }
}
Controller Action on Create Get
public IActionResult Create(int? processId)
{
// no value provided, so redirect to view that prompts for process
if (!processId.HasValue || processId == 0)
{
TempData["Error"] = "You must select a process to schedule";
return RedirectToAction("Processes");
}
var schedule = new Schedule()
{
ProcessId = processId.GetValueOrDefault(),
Process = _context.Processes.Find(processId.GetValueOrDefault()),
ScheduleNotifications = new List<ScheduleNotification>()
};
return View(schedule);
}
Razor view called on create
#model HangfireServer.Models.Schedule
#{
ViewData["Title"] = "Create";
}
<h1>Schedule</h1>
<hr />
<div class="row">
<div class="col">
<form asp-action="Create">
<div asp-validation-summary="ModelOnly" class="text-danger"></div>
<div class="text-danger" style="direction:rtl" asp-validation-summary="All"></div>
#Html.HiddenFor(m => m.ProcessId)
#Html.HiddenFor(m => m.Process)
<div class="form-group row">
<text class="control-label col-sm-2">#Html.DisplayNameFor(m => m.Process.Name)</text>
<div class="col-sm-4">
#Html.DisplayFor(m => m.Process.Name)
</div>
<text class="text-left col-sm-6 text-secondary">Process to schedule</text>
</div>
<div class="form-group row">
<label asp-for="StartDateTime" class="control-label col-sm-2"></label>
<div class="col-sm-4">
<input asp-for="StartDateTime" class="control-label" />
<span asp-validation-for="StartDateTime" class="text-danger"></span>
</div>
<text class="text-left col-sm-6 text-secondary">Date and time to initiate process</text>
</div>
<!-- more stuff -->>
<div class="form-group">
<input type="submit" value="Create" class="btn btn-primary" />
</div>
</form>
</div>
</div>
Create post controller
// POST: Schedules/Create
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create([Bind("ScheduleId,StartDateTime,Recurrence,Param1,Param2,Param3,Param4,Param5,Param6,Param7,ProcessId,Process,ScheduleNotifications")] Schedule schedule)
{
if (ModelState.IsValid)
{
// save the new schedule
schedule.Process = await _context.Processes.FindAsync(schedule.ProcessId);
_context.Add(schedule);
await _context.SaveChangesAsync();
// queue the new schedule
EnqueueProcess(schedule);
TempData["Success"] = $"Process {schedule.Process.Name} has been scheduled";
return RedirectToAction(nameof(Index));
}
// display additional errors not caught in page validation
string errorMessage = "";
foreach (var modelState in ViewData.ModelState.Values)
{
foreach (var error in modelState.Errors)
{
errorMessage = String.IsNullOrEmpty(errorMessage) ? error.ToString() : "<br>" + error.ToString();
}
}
TempData["Error"] = errorMessage;
// return to current view
return RedirectToAction("Create", new { processId = schedule.ProcessId });
}
On trace, the GET is passing to the view schedule with its parent process id and process object populated. On POST
ModelState.IsValid = False
schedule.processId = 2 (or whatever the value sent from GET was
schedule.process is null (even though there's a hidden field for process in vie)
ModelState only has 1 invalid key
SubKey={Process}, Key="Process", ValidationState=Invalid

Answer 1

I think I figured it out - but this is just a hack, there's probably a correct way to do it
// populate process property with an instance of a process object
schedule.Process = await _context.Processes.Include(p => p.Application).FirstOrDefaultAsync(p => p.ProcessId == schedule.ProcessId);
ModelState.Clear();
Then either
ModelState.Remove("Process");
Or
TryValidateModel(schedule);
Regardless ModelState.IsValid is now true