Does cocoon work with self-joins?

[ITS-Marcelo]

I'm having troubles understanding if cocoon can work with self-joins. I have the following setup:

class Project < ApplicationRecord
  has_many :allowed_items, class_name: "Project", foreign_key: "validator_id", inverse_of: :validator
  belongs_to :validator, class_name: "Project", inverse_of: :allowed_items, optional: true
  accepts_nested_attributes_for :allowed_items, allow_destroy: true

When I try to create a new project and make it have a validator_id of a per-existing project, I get the following error:

SQLite3::ConstraintException: NOT NULL constraint failed: projects.name

This is where I'm getting confused, from looking at the debug logs, it looks like a project is created with the name and target "s" (sorry for my lack of originality in naming). But then a second project is attempted to be created and fails due to not having a name or target specified. The logs specify that a validator_id was given through the form and it value is 131. The second project item that is attempted to be created has also has a validator_id assigned of value 217 (which I am assuming it is the recently created project). However, I don't want to create two projects. I want to create a project and associated to an existing project. I'll include the log message below:

Started POST "/projects" for 127.0.0.1 at 2025-01-21 10:29:39 -0800
Processing by ProjectsController#create as HTML
  Parameters: {"authenticity_token"=>"[FILTERED]", "project"=>{"name"=>"s", "target"=>"s", "allowed_items_attributes"=>{"1737484178511"=>{"validator_id"=>"131", "_destroy"=>"false"}}}, "commit"=>"Create Project"}
  TRANSACTION (0.0ms)  begin transaction
  ↳ app/controllers/projects_controller.rb:44:in `block in create'
  Project Create (0.5ms)  INSERT INTO "projects" ("name", "target", "created_at", "updated_at") VALUES (?, ?, ?, ?)  [["name", "s"], ["target", "s"], ["created_at", "2025-01-21 18:29:39.164287"], ["updated_at", "2025-01-21 18:29:39.164287"]]
  ↳ app/controllers/projects_controller.rb:44:in `block in create'
  Project Create (0.3ms)  INSERT INTO "projects" ("created_at", "updated_at", "validator_id") VALUES (?, ?, ?)  [["created_at", "2025-01-21 18:29:39.166303"], ["updated_at", "2025-01-21 18:29:39.166303"], ["validator_id", 217]]
  ↳ app/controllers/projects_controller.rb:44:in `block in create'

Any feedback would appreciated. Cheers.

[nathanvda]

In the posted params we see 1 project (to be created) with one allowed-item, also to be created.

So it attempts to create an allowed_item which is a Project, but the "allowed-item" has no name, and for a Project a name is required.

[ITS-Marcelo]

Right, so is there a way to tell it that the allowed_item already exists and that I want it to only create the association?