Using InboundNavigation in TrackGraph

Using TrackGraph, I would like to be able to set the state of an entity to Added if it is a child in a one-to-many relationship and the parent entity state is Added. For example, if an Order is in an Added state, then I would like to be able to set the OrderDetail to Added as well.

I notice that EntityEntryGraphNode has an InboundNavigation property. Is it possible to use it to find the relationship type and a pointer to the entity on the other side of the relationship?

[ajcvickers]

@tonysneed Something like this:

context.ChangeTracker.TrackGraph(blog, e =>
{
    if (e.InboundNavigation != null)
    {
        Debug.Assert(!e.InboundNavigation.IsDependentToPrincipal());

        var dependentEntry = e.Entry;
        var foreignKey = e.InboundNavigation.ForeignKey;

        var keyValues = foreignKey.Properties
            .Select(p => dependentEntry.Property(p.Name).CurrentValue)
            .ToArray();

        var principalEntry =
            dependentEntry.Context.Entry(
                dependentEntry.Context.Find(foreignKey.PrincipalEntityType.ClrType, keyValues));

        // Handle dependent
        dependentEntry.State = principalEntry.State == EntityState.Added
            ? EntityState.Added
            : EntityState.Unchanged;
    }
    else
    {
        // Handle principal
        e.Entry.State = e.Entry.IsKeySet ? EntityState.Unchanged : EntityState.Added;
    }
});

But that only works if the FK is mapped and an the property values are set before calling Add. See #7389.

[tonysneed]

@ajcvickers Thanks, this is helpful. However, I will need access to the referencing entity, as proposed in #7389, because the FK and parent entity may not have the key set because it is an auto-generated identity column.