POST to create through controller with different FK constraint than 'id' fails

Result versus expectation

Following the docs we created a dashboard for the below model, which is the "N" in a 1:N relationship between an OwningModel (1) and an OwnedModel (N). The catch is that the OwnedModel is keyed (FK) on a unique ID that is not owning_model_id, it's constrained on special_owner_id.

So, as below, we have

    owning_model: Field::BelongsTo.with_options(
      class_name: "SomeModule::OwningModel",
      foreign_key: 'special_owner_id'
    ),

When we submit a new "create" through the below dashboard, we get an FK error:

ActiveRecord::InvalidForeignKey (PG::ForeignKeyViolation: ERROR:  insert or update on table "owned_model" violates foreign key constraint "fk_rails_e9b0191624"

2022-03-28T18:05:01.013857+00:00 app[web.1]: DETAIL:  Key (special_owner_id)=(20) is not present in table "owning_models".

2022-03-28T18:05:01.013858+00:00 app[web.1]: : INSERT INTO "owned_models" ("special_owner_id", "attr_1", "created_at", "updated_at") VALUES ('20', 2500, '2022-03-28 18:05:00.837807', '2022-03-28 18:05:00.837807') RETURNING "id"):

The '20' in that log corresponds to owning_model.id, which is actually 20, but the default controller method for create in the administrate controller is POSTing as above with (special_owner_id)=(20). We expected it to POST with (special_owner_id)=(SOME_SPECIAL_ID), and succeed.

Workaround

One workaround is to modify the OwnedModel's dashboard as follows:

    owning_model: Field::BelongsTo.with_options(
      class_name: "SomeModule::OwningModel",
      foreign_key: 'special_owner_id',
      primary_key: 'special_owner_id',
    ),

However, this is semantically incorrect (that isn't the primary key), and will probably confuse developers later.

Dashboard model

require "administrate/base_dashboard"

class OwnedModelDashboard < Administrate::BaseDashboard
  NAMESPACE = 'internal'
  # ATTRIBUTE_TYPES
  # a hash that describes the type of each of the model's fields.
  #
  # Each different type represents an Administrate::Field object,
  # which determines how the attribute is displayed
  # on pages throughout the dashboard.
  ATTRIBUTE_TYPES = {
    owning_model: Field::BelongsTo.with_options(
      class_name: "SomeModule::OwningModel",
      foreign_key: 'special_owner_id'
    ),
    id: Field::Number,
    attr_1: Field::Boolean,
    attr_2: Field::Number,
    created_at: Field::DateTime,
    updated_at: Field::DateTime,
  }.freeze

  # COLLECTION_ATTRIBUTES
  # an array of attributes that will be displayed on the model's index page.
  COLLECTION_ATTRIBUTES = [
    :owning_model,
    :attr_1,
    :attr_2,
  ].freeze

  # SHOW_PAGE_ATTRIBUTES
  # an array of attributes that will be displayed on the model's show page.
  SHOW_PAGE_ATTRIBUTES = [
    :owning_model,
    :id,
    :attr_1,
    :attr_2,
    :created_at,
    :updated_at,
  ].freeze

  # FORM_ATTRIBUTES
  # an array of attributes that will be displayed
  # on the model's form (`new` and `edit`) pages.
  FORM_ATTRIBUTES = [
    :owning_model,
    :attr_1,
    :attr_2,
  ].freeze

Environment

• Rails 5
• administrate 0.17