That sort of dynamic relationship isn’t how has_one is meant to work. You have to manually control a has_one such as: When you add a new comment, you would unset the current latest_comment and then set the new entry as the latest_comment.

What you’re thinking would take the shape of a virtual: true field, and you’d define a query like above. When you load the struct, you’d then run a separate query for the latest_comment, and populate the virtual field.

Hey @lorenzomar the general challenge with this is when you are dealing with a collection of users and you want to get the most recent approved comment for each of them. This is doable with a lateral join, but at least last I looked Ecto won’t do this for you.

What will happen in the case of a has_one with a preload_order is that it will load ALL comments and then get the first one in memory. This is going to be a foot gun when you get more records.