adding some parent CRUD

app/models/child.rb

@@ -5,6 +5,17 @@ class Child < ActiveRecord::Base
   validates :first_name, presence: true
   validates :last_name, presence: true
 
+  scope :not_related_to, lambda { |parent_id|
+    joins("LEFT JOIN (
+          SELECT child_id
+          FROM parenthoods
+          WHERE person_id = #{sanitize(parent_id)}
+        ) as s1 on s1.child_id = children.id")
+      .where("s1.child_id is null")
+      .order(:first_name, :last_name)
+      .uniq
+  }
+
   def name
     "#{first_name} #{last_name}"
   end

app/models/person.rb

@@ -1,10 +1,11 @@
 class Person < ActiveRecord::Base
   has_many :parenthoods
   has_many :children, through: :parenthoods
-  accepts_nested_attributes_for :children
+  accepts_nested_attributes_for :children, reject_if: :all_blank
 
   validates :first_name, presence: true
   validates :last_name, presence: true
+  validates :phone, presence: true
 
   scope :with_name, lambda { |name|
     where("concat(first_name, ' ', last_name) RLIKE ?", name)