One Field Refuses to Update Using EF - asp.net-mvc

Question

I have an unusual problem. One field in the database (FK_ItemType) will not update itself. I went into the vs debug, and checked that int ItemType was assigned, that it found a record in the database, that it assigned that record to item.FK_ItemType, and that that record stayed attached all the way to db.SaveChanges() (I used a breakpoint to check the value of item.FK_ItemType at db.Entry(item).State = EntityState.Modified;
To be extra sure, immediately after I commented out my redirect and pulled the record from the database and checked what the value was, returning that instead of the redirect. It returns the correct value.
However, when I look in the database, or go to my listing page, the newly updated ItemType is not there (still NULL in the database). Even more puzzling, everything works perfectly fine when adding a record.
Here are the relevant sections of my controller and model
[HttpPost]
public ActionResult Edit(Item item, int Company = 0, int Service = 0, int ItemType = 0)
{
if (Request.Form["doDelete"] == "true")
return Delete(item);
//Get, assign foreign keys
Company c = db.Companies.Find(Company);
Service s = db.Services.Find(Service);
ItemType i = db.ItemTypes.Find(ItemType);
if (c != null)
item.FK_Company = c;
if (s != null)
item.FK_Service = s;
if (i != null)
item.FK_ItemType = i;
//Force revalidate
ModelState.Clear();
//TryUpdateModel(item);
TryValidateModel(item);
if (ModelState.IsValid)
{
if (item.ItemID == 0) //add
db.Items.Add(item);
else
{
db.Entry(item).State = EntityState.Modified;
}
db.SaveChanges();
Item i2 = db.Items.Find(item.ItemID);
Response.Write(i2.FK_ItemType.Name);
return null;
// Return to the listing page, and show the user the filters they were looking at before editing.
return Redirect("~/" + Request.RequestContext.RouteData.Values["Controller"].ToString() + "/Index/" + Request.Form["ref"]);
}
// There was a validation error
if (item.ItemID != 0)
return Update(item);
else
return Add(item);
}
Model
public class Item
{
public int ItemID { get; set; }
...
[Required]
[Display(Name="Company")]
public virtual Company FK_Company { get; set; }
[Required]
[Display(Name="Service")]
public virtual Service FK_Service { get; set; }
[Display(Name="Item Type")]
public virtual ItemType FK_ItemType { get; set; }
}

Answer 1

Despite the name FK_ItemType this property is not a FK (foreign key) property. It is a navigation property and relationships represented by navigation properties are not updated when you set the state to Modified. (The same applies to FK_Company and FK_Service.)
You can either introduduce "real" foreign key properties...
[ForeignKey("FK_ItemType")]
public int RealFK_ItemType { get; set; }
public virtual ItemType FK_ItemType { get; set; }
// please give those properties better names..., like "ItemTypeID" and "ItemType"
...and then use the FK RealFK_ItemType directly to change relationships.
Or you must load the original Item from the database first (including related entities) to change the relationships by setting the navigation properties. The code for the UPDATE would be something like this:
var itemIdDb = db.Items
.Include(i => i.Company)
.Include(i => i.Service)
.Include(i => i.ItemType)
.Single(i => i.ItemID == item.ItemID);
Company c = db.Companies.Find(Company);
Service s = db.Services.Find(Service);
ItemType i = db.ItemTypes.Find(ItemType);
if (c != null)
itemInDb.FK_Company = c;
if (s != null)
itemInDb.FK_Service = s;
if (i != null)
itemInDb.FK_ItemType = i;
db.Entry(itemInDb).CurrentValues.SetValues(item);
db.SaveChanges();