Rails Model has_many with multiple foreign_keys

Question

Relatively new to rails and trying to model a very simple family \"tree\" with a single Person model that has a name, gender, father_id and mother_id (2 parents). Below is b

Answer 1

I prefer to use scopes for this issue. Like this:

class Person < ActiveRecord::Base
  belongs_to :father, :class_name => 'Person'
  belongs_to :mother, :class_name => 'Person'
  has_many :children_of_father, :class_name => 'Person', :foreign_key => 'father_id'
  has_many :children_of_mother, :class_name => 'Person', :foreign_key => 'mother_id'

  scope :children_for, lambda {|father_id, mother_id| where('father_id = ? AND mother_id = ?', father_id, mother_id) }
end

This trick make it easy to get children without use instances:

Person.children_for father_id, mother_id

Answer 2

My answer to Associations and (multiple) foreign keys in rails (3.2) : how to describe them in the model, and write up migrations is just for you!

As for your code,here are my modifications

class Person < ActiveRecord::Base
  belongs_to :father, :class_name => 'Person'
  belongs_to :mother, :class_name => 'Person'
  has_many :children, ->(person) { unscope(where: :person_id).where("father_id = ? OR mother_id = ?", person.id, person.id) }, class_name: 'Person'
end

So any questions?