Ecto Associations JSON displaying question

The three backticks ``` (on new lines) are the best way to format code blocks IMO. When you only want to format a smaller sentence (or a single word) use the single backtick `.

What you want to show seems is not really related to your question. You say you want to show a post of a given user, and then show all other posts by that user? Then the preload makes no sense. It would if you would like to ouput the user with all his posts.

If you just want to show one posts and then a list of all other posts, I would handle it another way. Just fetch all posts, single out the post you want and put the rest as a property on a struct. If this is what you want I can try to make an example. Maybe even in one query.

Anyway, regarding the view, you could do it like this:

I think that you should put the preload() call after calling the Repo.all. I usually just inner_join. In your view you just need to loop over the users as well.

For example, here is the controller code:

user = User |> Repo.all() |> Preload(:posts)
render(conn, "user.json", user: user)

Then the view could be:

def render("user.json", %{user: user}) do
  %{
    id: user.id,
    username: user.username
    posts: render_may(user.posts, __MODULE__, "post.json", as: :post)       
  }
end

def render("post.json", %{post: post}) do
  %{
    id: post.id,
    content: post.content
  }
end