Add EnterpriseRelationship. An Enterprise can find its relatives.

app/models/enterprise.rb

@@ -127,6 +127,15 @@ class Enterprise < ActiveRecord::Base
     "#{id}-#{name.parameterize}"
   end
 
+  def relatives
+    Enterprise.where("
+      enterprises.id IN
+        (SELECT child_id FROM enterprise_relationships WHERE enterprise_relationships.parent_id=?)
+      OR enterprises.id IN
+        (SELECT parent_id FROM enterprise_relationships WHERE enterprise_relationships.child_id=?)
+    ", self.id, self.id)
+  end
+
   def distributed_variants
     Spree::Variant.joins(:product).merge(Spree::Product.in_distributor(self)).select('spree_variants.*')
   end

app/models/enterprise_relationship.rb

@@ -0,0 +1,7 @@
+class EnterpriseRelationship < ActiveRecord::Base
+  belongs_to :parent, class_name: 'Enterprise'
+  belongs_to :child, class_name: 'Enterprise'
+
+  validates_presence_of :parent_id, :child_id
+  validates_uniqueness_of :child_id, scope: :parent_id
+end

db/migrate/20140514044959_create_enterprise_relationships.rb

@@ -0,0 +1,16 @@
+class CreateEnterpriseRelationships < ActiveRecord::Migration
+  def change
+    create_table :enterprise_relationships do |t|
+      t.integer :parent_id
+      t.integer :child_id
+    end
+
+    add_index :enterprise_relationships, :parent_id
+    add_index :enterprise_relationships, :child_id
+
+    add_index :enterprise_relationships, [:parent_id, :child_id], unique: true
+
+    add_foreign_key :enterprise_relationships, :enterprises, column: :parent_id
+    add_foreign_key :enterprise_relationships, :enterprises, column: :child_id
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20140430020639) do
+ActiveRecord::Schema.define(:version => 20140514044959) do
 
   create_table "adjustment_metadata", :force => true do |t|
     t.integer "adjustment_id"
@@ -195,6 +195,15 @@ ActiveRecord::Schema.define(:version => 20140430020639) do
   add_index "enterprise_groups_enterprises", ["enterprise_group_id"], :name => "index_enterprise_groups_enterprises_on_enterprise_group_id"
   add_index "enterprise_groups_enterprises", ["enterprise_id"], :name => "index_enterprise_groups_enterprises_on_enterprise_id"
 
+  create_table "enterprise_relationships", :force => true do |t|
+    t.integer "parent_id"
+    t.integer "child_id"
+  end
+
+  add_index "enterprise_relationships", ["child_id"], :name => "index_enterprise_relationships_on_child_id"
+  add_index "enterprise_relationships", ["parent_id", "child_id"], :name => "index_enterprise_relationships_on_parent_id_and_child_id", :unique => true
+  add_index "enterprise_relationships", ["parent_id"], :name => "index_enterprise_relationships_on_parent_id"
+
   create_table "enterprise_roles", :force => true do |t|
     t.integer "user_id"
     t.integer "enterprise_id"
@@ -1005,6 +1014,9 @@ ActiveRecord::Schema.define(:version => 20140430020639) do
   add_foreign_key "enterprise_groups_enterprises", "enterprise_groups", name: "enterprise_groups_enterprises_enterprise_group_id_fk"
   add_foreign_key "enterprise_groups_enterprises", "enterprises", name: "enterprise_groups_enterprises_enterprise_id_fk"
 
+  add_foreign_key "enterprise_relationships", "enterprises", name: "enterprise_relationships_child_id_fk", column: "child_id"
+  add_foreign_key "enterprise_relationships", "enterprises", name: "enterprise_relationships_parent_id_fk", column: "parent_id"
+
   add_foreign_key "enterprise_roles", "enterprises", name: "enterprise_roles_enterprise_id_fk"
   add_foreign_key "enterprise_roles", "spree_users", name: "enterprise_roles_user_id_fk", column: "user_id"
 

spec/models/enterprise_spec.rb

@@ -26,6 +26,17 @@ describe Enterprise do
 
       Spree::Product.where(id: p.id).should be_empty
     end
+
+    describe "relationships to other enterprises" do
+      it "finds relatives" do
+        e, p, c = create(:enterprise), create(:enterprise), create(:enterprise)
+
+        EnterpriseRelationship.create! parent_id: p.id, child_id: e.id
+        EnterpriseRelationship.create! parent_id: e.id, child_id: c.id
+
+        e.relatives.sort.should == [p, c].sort
+      end
+    end
   end
 
   describe "validations" do