MVC4 EF5 entity property not updating on SaveChanges() - asp.net

Question

I've been reading through lots of articles trying to learn MVC4, but I'm stumped as to why my entity is not getting updated to database.
I've been trying to modify the MVC4 VS2012 Internet template.
So, here's the Controller action:
[HttpPost, ActionName("Approve")]
[Authorize]
public ActionResult ApproveConfirmed(long id)
{
using (StudentiContext context = new StudentiContext())
{
// context.Configuration.AutoDetectChangesEnabled = false;
var studente = (from d in context.STUDENTI_STRANIERI_MASTER_REG
where d.ID_PERSONA == id
select d).Single();
STUDENTI_STRANIERI_MASTER_REG st2 = studente;
st2.ESITO = 1;
//studente.ESITO = 1;
var statos = context.Entry(studente).State;
Console.WriteLine("Before DetectChanges: {0}",statos);
//context.ChangeTracker.DetectChanges();
context.Entry(studente).State = EntityState.Modified;
context.Entry(studente).CurrentValues.SetValues(st2);
// var tracked = context.ChangeTracker.Entries();
context.Entry(studente).Property( o => o.ESITO ).IsModified = true;
TryUpdateModel(studente);
context.SaveChanges();
Console.WriteLine("After DetectChanges: {0}",statos);
return RedirectToAction("PrivateIndex");
}
}
The aim is just to update one property, ESITO and set it to 1. Currently its value is 2.
This is the model:
namespace MvcStudenti2.Models
{
using System;
using System.Collections.Generic;
public partial class STUDENTI_STRANIERI_MASTER_REG
{
public long ID_PERSONA { get; set; }
public string COGNOME { get; set; }
public string NOME { get; set; }
public string SESSO { get; set; }
public System.DateTime DATA_NASCITA { get; set; }
public long ID_STATO_NASCITA { get; set; }
public string LUOGO_NASCITA_ESTERO { get; set; }
public string CODICE_FISCALE { get; set; }
public string TITOLO_POSSEDUTO { get; set; }
public Nullable<short> DURATA_TITOLO { get; set; }
public string VOTAZIONE { get; set; }
public string UNI_PROVENIENZA { get; set; }
public long ID_STATO_UNI { get; set; }
public string CERT_LINGUISTICA { get; set; }
public string CERT_PUNTEGGIO { get; set; }
public string NOTE { get; set; }
public System.DateTime DATA_RICHIESTA { get; set; }
public short ESITO { get; set; }
public string CDS_COD { get; set; }
public string EMAIL { get; set; }
public string NUMERO_TELEFONO { get; set; }
public string INDIRIZZO { get; set; }
public string CAP_INDIRIZZO { get; set; }
public string CITTA { get; set; }
public long ID_STATO_INDIRIZZO { get; set; }
public string DESCRIZIONE_CIT_NAZ { get; set; }
public Nullable<System.DateTime> DATA_COMPLETAMENTO_ATTESO { get; set; }
public Nullable<System.DateTime> ANNO_COMPLETAMENTO { get; set; }
public Nullable<short> DURATA_CORSO_COMPLETATO { get; set; }
public decimal GPA { get; set; }
public string ALTRI_TITOLI { get; set; }
public string MADRELINGUA { get; set; }
public Nullable<short> CERT_TOEFL_PUNT { get; set; }
public string CERT_FIRSTCERT_GRADE { get; set; }
public Nullable<short> CERT_FIRSTCERT_PUNT { get; set; }
public byte[] FILE_CV { get; set; }
public byte[] FILE_CARRIERA { get; set; }
public byte[] FILE_CERT_LINGUA { get; set; }
public byte[] FILE_DOC_IDENTITA { get; set; }
public string PWD { get; set; }
public string FILE_CV_NOME { get; set; }
public string FILE_CARRIERA_NOME { get; set; }
public string FILE_CERT_LINGUA_NOME { get; set; }
public string FILE_DOC_IDENTITA_NOME { get; set; }
public string FILE_CV_TIPO { get; set; }
public string FILE_CARRIERA_TIPO { get; set; }
public string FILE_CERT_LINGUA_TIPO { get; set; }
public string FILE_DOC_IDENTITA_TIPO { get; set; }
public Nullable<short> STATO { get; set; }
public Nullable<short> VALUTATO { get; set; }
public Nullable<short> ARCHIVIATO { get; set; }
public string CDS_COD_2 { get; set; }
public Nullable<short> MAIL_INVIATA { get; set; }
public string LINK_ULTIMO_CORSO { get; set; }
public Nullable<short> ATTIVO { get; set; }
public byte[] FILE_LETTERA_ACCETTAZIONE { get; set; }
public string FILE_LETTERA_ACCETTAZIONE_NOME { get; set; }
public string FILE_LETTERA_ACCETTAZIONE_TIPO { get; set; }
}
}
Everywhere I read I find that SaveChanges() should be enough, possibly after the EntityState.Modified.
I can correctly edit the entity, if I pass the whole entity to the Action, but in this case the Approve view is a built on a Detail template, so I don't have anything to POST from it (and I'd prefer not to: I could insert a hidden field and post just that, but I'm trying to update a single filed from code, and I'm not sure if the whole entity would get updated or overwritten ).
statos goes to "modified", if I understand correctly, because I have done a query on the entity.
Another thing I don't understand is why ESITO gets update -also- in studente, but then reverts to "2" after SaveChanges().
Are property changes being detected? I've wrapped every Action in a using block, as suggested elsewhere, so not to have multiple contextx/instances around.
Could anyone please point me to what I'm doing wrong? The code above is probably over-redundant, but I've been trying everything I have found on SO.
Thanks, everyone.

Answer 1

The following is all that is required to change the ESITO property.
[HttpPost, ActionName("Approve")]
[Authorize]
public ActionResult ApproveConfirmed(long id)
{
using (StudentiContext context = new StudentiContext())
{
// context.Configuration.AutoDetectChangesEnabled = false;
var studente = (from d in context.STUDENTI_STRANIERI_MASTER_REG
where d.ID_PERSONA == id
select d).Single();
studente.ESITO = 1;
context.SaveChanges();
return RedirectToAction("PrivateIndex");
}
}