EF 6 Delete Orphan Entities

gistfile1.txt

    public interface IDeleteOrphans
    {
        void DeleteOrphanedEntries();
    }

    public class DeleteOrphans<T> : IDeleteOrphans
        where T : DbContext, IObjectContextAdapter
    {
        private readonly T _contextAdapter;
        private readonly IList<PropertyInfo> _propertyInfos;

        public DeleteOrphans(T contextAdapter)
        {
            _contextAdapter = contextAdapter;
            var entitySets = _contextAdapter.ObjectContext.MetadataWorkspace.GetEntityContainer(contextAdapter.ObjectContext.DefaultContainerName, DataSpace.CSpace).EntitySets;
            var typeAssemblies = Assembly.GetAssembly(contextAdapter.GetType()).GetTypes();
            _propertyInfos = entitySets.SelectMany(es => GetNavigationProperties(es,typeAssemblies)).ToList();
        }

        private IEnumerable<PropertyInfo> GetNavigationProperties(EntitySet entitySet, Type[] typeAssemblies)
        {
            var type = typeAssemblies.First(t => t.Name == entitySet.ElementType.Name); 
            return entitySet.ElementType.DeclaredNavigationProperties.Select(p => type.GetProperty(p.Name)).ToList();
        }

        protected virtual IEnumerable<DbEntityEntry> OrphanedEntries
        {
            get { return _contextAdapter.ChangeTracker.Entries().Where(IsOrphaned).ToList(); }
        }

        private bool IsOrphaned(DbEntityEntry entity)
        {
            if (entity.State != EntityState.Modified)
                return false;
            return _propertyInfos.Where(p => p.DeclaringType.IsInstanceOfType(entity.Entity)).Any(p => p.GetValue(entity.Entity) == null);
        }

        public void DeleteOrphanedEntries()
        {
            foreach (var orphanedEntry in OrphanedEntries)
                orphanedEntry.State = EntityState.Deleted;
        }
    }