Entity Framework says property is null when updating entity

Question

I'm trying to add a new entity to an existing collection. But when doing so the 'parent' entity complains the other navigational properties are null (although they aren't).

Error:

An exception of type 'System.Data.Entity.Validation.DbEntityValidationException' occurred in Ela.Facade.dll but was not handled in user code

Additional information: Validation failed for one or more entities. See 'EntityValidationErrors' property for more details.

Fund State: Modified

Error: Field Owner is required

When debugging the field Owner is loaded correctly:

Fund class:

public class Fund
{
    public int FundId { get; set; }

    [Required]
    [Index("IDX_FundName", 2, IsUnique = true)]
    [MaxLength(25)]
    public string Name { get; set; }

    [Required]
    [Index("IDX_FundIdentifier", 2, IsUnique = true)]
    [MaxLength(25)]
    public string Identifier { get; set; }

    public double Balance { get; set; }

    [Required]
    [Index("IDX_FundName", 1, IsUnique = true)]
    [Index("IDX_FundIdentifier", 1, IsUnique = true)]
    public virtual ApplicationUser Owner { get; set; }

    public virtual ICollection<Transaction> Transactions { get; set; }

    public Fund()
    {
        Transactions = new List<Transaction>();
    }
}

CreateTransaction method:

public Transaction CreateTransaction(Transaction newTransaction)
{
    var context = new ApplicationDbContext();
    try
    {
        var fund = context.Funds.FirstOrDefault(f => f.FundId == newTransaction.ToFund.FundId);
        newTransaction.ToFund = fund;
        fund.Transactions.Add(newTransaction);
        context.SaveChanges();
    }
    catch (DbEntityValidationException e)
    {
        foreach (var eve in e.EntityValidationErrors)
        {
            Console.WriteLine("Entity of type \"{0}\" in state \"{1}\" has the following validation errors:",
                eve.Entry.Entity.GetType().Name, eve.Entry.State);
            foreach (var ve in eve.ValidationErrors)
            {
                Console.WriteLine("- Property: \"{0}\", Error: \"{1}\"",
                    ve.PropertyName, ve.ErrorMessage);
            }
        }
        throw;
    }
    return context.Transactions.FirstOrDefault();
}

Any help or recommendations are appreciated!

Answer 1

When you look up the fund, it does not populate the foreign key properties if they are virtual. In order to have them pulled you have to include that property; doing so will allow you to get the desired results.

var fund = 
    context.Funds
           .Include(f => f.Owner)
           .FirstOrDefault(f => f.FundId == newTransaction.ToFund.FundId);

You can find additional information about how EF loads related entities in this MSDN article

Answer 2

Sounds like you are missing the owner from the db context. You can't just new up the owner:

var fund = context.Funds.FirstOrDefault(f => f.FundId == newTransaction.ToFund.FundId);
newTransaction.ToFund = fund;
var owner = context.Owners.First(x => x.OwnerId == newTransaction.Owner.OwnerId);
newTransaction.Owner = owner;
fund.Transactions.Add(newTransaction);

One other alternative is to Attach the entity.