Entity Framework 6 dbContext not saving changes - entity-framework

Question

In our MVC 5 project our database context is instantiate in the AccountController like this
private CustomersContext _customersContext;
public CustomersContext CustContext
{
get
{
return _customersContext ?? new CustomersContext();
}
private set
{
_customersContext = value;
}
}
Each customer is referred by a number of sources. The routine below changes the UserId of the referral source to a new user.
var referralList = CustContext.Referrals.Where(d => d.UserId == membershipUser.Id);
foreach (Referral referral in referralList)
{
referral.UserId = newUser.Id;
}
Stepping trough the code I can see referral.UserId being updated. However
var result = await CustContext.SaveChangesAsync();
returns 0. The database is not updated.
CustomersContext looks like this
{
public partial class CustomersContext : IdentityDbContext<ApplicationUser>//, ICustomersContext
{
public CustomersContext()
: base("DefaultConnection", throwIfV1Schema: false)
{
}
public static CustomersContext Create()
{
return new CustomersContext();
}
public virtual DbSet<ReferralSource> ReferralSources { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<ApplicationUser>()
.HasMany(e => e.Referrals)
.WithRequired(e => e.User)
.HasForeignKey(e => e.UserId)
.WillCascadeOnDelete(false);
I don't see any sql emitted in SQL Profiler. Why doesn't the database context save changes?

Answer 1

Before calling var result = await CustContext.SaveChangesAsync(); you need to set the state of the entities that you want to be modified. Somthing like:
var referralList = CustContext.Referrals.Where(d => d.UserId == membershipUser.Id);
foreach (Referral referral in referralList)
{
referral.UserId = newUser.Id;
CustContext.Entry(referral).State = System.Data.Entity.EntityState.Modified;
}
var result = await CustContext.SaveChangesAsync();

Answer 2

The answer provided by #Issac did not solve my problem, but it did put me on the road to a solution. The error
An entity object cannot be referenced by multiple instances of IEntityChangeTracker.
suggested there were multiple instances of dbContext. I removed the context from the CTOR and instantiated the context within a using statement
using (CustomersContext customersContext = new CustomersContext())
{
var referralList = customersContext.Referrals.Where(d => d.UserId == membershipUser.Id);
foreach (Referral referral in referralList)
{
referral.UserId = newUser.Id;
}
var result = await customersContext.SaveChangesAsync();
}
and now all is tickety-boo