Stateful navigation in associations

Hi,

Just wondering if the tests below can be passed in LightSpeed or not.

public void AddingPostAssignsBlog() {
  Blog b = new Blog();
  Post p1 = new Post();
  Post p2 = new Post();

  b.Posts.Add(p1); // Not this: b.AddPost(p1)
  b.Posts.Add(p2);

  Assert.AreSame(b, p1.Blog);
  Assert.AreSame(b, p2.Blog);

public void AddingBlogAssignsPost() {
  Blog b = new Blog();
  Post p1 = new Post();
  Post p2 = new Post();

  p1.Blog = b;
  p2.Blog = b;

  Assert.AreEqual(2, b.Posts.Count);

}

The actual question is if the navigation in associations is stateful (when you change something - it gets reflected on all dependants)?

And how LightSpeed does behave in this case (when trying to save all objects):
  Blog b1 = new Blog();
  Blog p2 = new Blog();
  Post p = new Post();
  p.Blog = b1; // p is in b1
  b2.Posts.Add(b); // b is in b2!!

 

Thanks,
Dmitriy.

Hi Dmitriy,

Your first two tests will pass.  Adding an entity (e.g. a Post) to another entity's association collection (Blog.Posts) automatically wires up the backreference (Post.Blog); and setting the backreference automatically adds the child to the collection of the new parent (and removes it from the collection of the previous parent if it had one).

In your final scenario, I'm not 100% sure because there are a couple of typos which make me unsure about what is a Post and what is a Blog, but I think what you are asking about is something like this:

Blog blog1 = new Blog():
Blog blog2 = new Blog():
Post post = new Post();
post.Blog = blog1;  // assigning post to blog1
blog2.Posts.Add(post);  // assigning post to blog2

If that's the scenario, the answer is last one wins.  blog2.Posts.Add implicitly removes post from blog1.Posts, and sets post.Blog to blog2.  So you would end up with blog1 containing no posts and blog2 containing one post.

If I've misunderstood, please let me know!