Adding a unit test to demonstrate and detect issue #130.

GraphDiff/GraphDiff.Tests/Models/TestModels.cs

@@ -112,6 +112,24 @@ public class NullableKeyModel
         public Guid? Id { get; set; }
     }
 
+    public class PKFKModelPrimary
+    {
+        [Key]
+        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+        public int? Id { get; set; }
+
+        public PKFKModelSecondary Secondary { get; set; }
+        public string Name { get; set; }
+    }
+
+    public class PKFKModelSecondary
+    {
+        [Key]
+        [DatabaseGenerated(DatabaseGeneratedOption.None)]
+        public int? Id { get; set; }
+        public string Name { get; set; }
+    }
+
     // ====================================
     // Second tier models
     // ====================================

GraphDiff/GraphDiff.Tests/TestDbContext.cs

@@ -4,8 +4,8 @@
 
 namespace RefactorThis.GraphDiff.Tests
 {
-	public class TestDbContext : DbContext
-	{
+    public class TestDbContext : DbContext
+    {
         public IDbSet<TestNode> Nodes { get; set; }
         public IDbSet<TestNodeWithBaseReference> NodesWithReference { get; set; }
 
@@ -16,7 +16,7 @@ public class TestDbContext : DbContext
         public IDbSet<OneToManyAssociatedModel> OneToManyAssociatedModels { get; set; }
         public IDbSet<OneToManyOwnedModel> OneToManyOwnedModels { get; set; }
 
-	    public IDbSet<MultiKeyModel>  MultiKeyModels { get; set; }
+        public IDbSet<MultiKeyModel>  MultiKeyModels { get; set; }
 
         public IDbSet<RootEntity> RootEntities { get; set; }
 
@@ -25,8 +25,11 @@ public class TestDbContext : DbContext
         public IDbSet<InternalKeyModel> InternalKeyModels { get; set; }
         public IDbSet<NullableKeyModel> NullableKeyModels { get; set; }
 
-		protected override void OnModelCreating(DbModelBuilder modelBuilder)
-		{
+        public IDbSet<PKFKModelPrimary> PKFKModelPrimaries { get; set; }
+        public IDbSet<PKFKModelSecondary> PKFKModelSecondaries { get; set; }
+
+        protected override void OnModelCreating(DbModelBuilder modelBuilder)
+        {
             // second tier mappings
 
             modelBuilder.Entity<TestNode>().HasOptional(p => p.OneToOneAssociated).WithOptionalPrincipal(p => p.OneParent);
@@ -61,9 +64,11 @@ protected override void OnModelCreating(DbModelBuilder modelBuilder)
 
             modelBuilder.Entity<InternalKeyModel>()
                     .HasMany(ikm => ikm.Associates)
-		            .WithRequired(ikm => ikm.Parent);
-		}
+                    .WithRequired(ikm => ikm.Parent);
+
+            modelBuilder.Entity<PKFKModelPrimary>().HasOptional(p => p.Secondary).WithRequired();
+        }
 
-		public TestDbContext() : base("GraphDiff") {}
-	}
+        public TestDbContext() : base("GraphDiff") {}
+    }
 }

GraphDiff/GraphDiff.Tests/Tests/OwnedEntityBehaviours.cs

@@ -105,5 +105,31 @@ public void ShouldRemoveEntityIfRemovedFromParent()
                 Assert.IsNull(context.OneToOneOwnedModels.SingleOrDefault(p => p.Id == oneToOne.Id));
             }
         }
+
+        [TestMethod]
+        public void ShouldCreateEntityWhenParentCreated_NullablePkFk()
+        {
+            var primary = new PKFKModelPrimary()
+            {
+                Name = "Primary",
+                Secondary = new PKFKModelSecondary()
+                {
+                    Name = "Secondary"
+                }
+            };
+
+            PKFKModelPrimary persisted = null;
+
+            using (var context = new TestDbContext())
+            {
+                persisted = context.UpdateGraph<PKFKModelPrimary>(primary, mapping => mapping.OwnedEntity(p => p.Secondary));
+                context.SaveChanges();
+            }
+
+            Assert.IsNotNull(persisted);
+            Assert.AreEqual(persisted.Id, persisted.Secondary.Id);
+            Assert.AreEqual(primary.Name, persisted.Name);
+            Assert.AreEqual(primary.Secondary.Name, persisted.Secondary.Name);
+        }
     }
 }