solve conflicts

app/models/collection.rb

@@ -40,7 +40,7 @@ class Collection < ApplicationRecord
   has_many :learning_objects, through: :collection_items, source: :collectionable, source_type: 'LearningObject'
   has_many :collection_items
 
-  belongs_to :owner, polymorphic: true
+  belongs_to :owner, polymorphic: true, counter_cache: true
 
   validates :name, :owner, presence: true
   validates_inclusion_of :privacy, in: %w(public private), message: 'Privacy must be public or private'

app/models/learning_object.rb

@@ -52,7 +52,7 @@ class LearningObject < ApplicationRecord
   has_many :collections, through: :collection_items
   has_many :attachments, class_name: 'LearningObject::Attachment', autosave: true # autosave to allow import
 
-  belongs_to :publisher, polymorphic: true
+  belongs_to :publisher, polymorphic: true, counter_cache: true
   belongs_to :language
   belongs_to :license
   belongs_to :object_type

app/models/like.rb

@@ -16,7 +16,7 @@ class Like < ApplicationRecord
   include Trackable
 
   belongs_to :likeable, polymorphic: true, counter_cache: true
-  belongs_to :user
+  belongs_to :user, counter_cache: true
 
   validates_presence_of :user, :likeable
   validates :user_id, uniqueness: { scope: [:likeable_id, :likeable_type] }

app/serializers/collection_serializer.rb

 class CollectionSerializer < ActiveModel::Serializer
   cache key: 'collection', expires_in: 4.hours
-  attributes :id, :name, :owner, :created_at, :updated_at, :description, :privacy, :score
+  attributes :id, :name, :owner, :created_at, :updated_at, :description, :privacy, :score, :likes_count, :review_average, :thumbnail
   has_many :tags
   has_many :subjects
   has_many :educational_stages

app/serializers/user_serializer.rb

 class UserSerializer < ActiveModel::Serializer
   cache key: 'user', expires_in: 4.hours
-  attributes :id, :email, :name, :description, :created_at, :updated_at, :role_ids, :institution_ids, :avatar
-  # has_many :roles
-  # has_many :institutions
+  attributes :id, :email, :provider, :name, :description, :role_ids, :institution_ids, :avatar, :likes_count, :follows_count, :learning_objects_count, :collections_count, :created_at, :updated_at
 end

db/migrate/20161125134057_add_counts_to_user.rb

+class AddCountsToUser < ActiveRecord::Migration[5.0]
+  def change
+    add_column :users, :likes_count, :integer, default: 0
+    add_column :users, :learning_objects_count, :integer, default: 0
+    add_column :users, :collections_count, :integer, default: 0
+  end
+end

db/migrate/20161125153200_add_review_average_to_collection.rb

+class AddReviewAverageToCollection < ActiveRecord::Migration[5.0]
+  def change
+    add_column :collections, :review_average, :float, default: 0.0
+  end
+end