Add position attribute to relation between exercise collection and exercises

app/models/exercise.rb

@@ -14,7 +14,8 @@ class Exercise < ActiveRecord::Base
 
   has_and_belongs_to_many :proxy_exercises
   has_many :user_proxy_exercise_exercises
-  has_and_belongs_to_many :exercise_collections
+  has_many :exercise_collection_items
+  has_many :exercise_collections, through: :exercise_collection_items
   has_many :user_exercise_interventions
   has_many :interventions, through: :user_exercise_interventions
   has_many :exercise_tags

app/models/exercise_collection.rb

@@ -1,7 +1,8 @@
 class ExerciseCollection < ActiveRecord::Base
   include TimeHelper
 
-  has_and_belongs_to_many :exercises
+  has_many :exercise_collection_items
+  has_many :exercises, through: :exercise_collection_items
   belongs_to :user, polymorphic: true
 
   def exercise_working_times

app/models/exercise_collection_item.rb

@@ -0,0 +1,4 @@
+class ExerciseCollectionItem < ActiveRecord::Base
+  belongs_to :exercise_collection
+  belongs_to :exercise
+end

db/migrate/20180703125302_create_exercise_collection_items.rb

@@ -0,0 +1,13 @@
+class CreateExerciseCollectionItems < ActiveRecord::Migration
+  def up
+    rename_table :exercise_collections_exercises, :exercise_collection_items
+    add_column :exercise_collection_items,  :position, :integer, default: 0, null: false
+    add_column :exercise_collection_items,  :id, :primary_key
+  end
+
+  def down
+    remove_column :exercise_collection_items,  :position
+    remove_column :exercise_collection_items,  :id
+    rename_table :exercise_collection_items, :exercise_collections_exercises
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20180515110030) do
+ActiveRecord::Schema.define(version: 20180703125302) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -114,6 +114,15 @@ ActiveRecord::Schema.define(version: 20180515110030) do
     t.boolean  "network_enabled"
   end
 
+  create_table "exercise_collection_items", force: :cascade do |t|
+    t.integer "exercise_collection_id"
+    t.integer "exercise_id"
+    t.integer "position",               default: 0, null: false
+  end
+
+  add_index "exercise_collection_items", ["exercise_collection_id"], name: "index_exercise_collection_items_on_exercise_collection_id", using: :btree
+  add_index "exercise_collection_items", ["exercise_id"], name: "index_exercise_collection_items_on_exercise_id", using: :btree
+
   create_table "exercise_collections", force: :cascade do |t|
     t.string   "name"
     t.datetime "created_at"
@@ -125,14 +134,6 @@ ActiveRecord::Schema.define(version: 20180515110030) do
 
   add_index "exercise_collections", ["user_type", "user_id"], name: "index_exercise_collections_on_user_type_and_user_id", using: :btree
 
-  create_table "exercise_collections_exercises", id: false, force: :cascade do |t|
-    t.integer "exercise_collection_id"
-    t.integer "exercise_id"
-  end
-
-  add_index "exercise_collections_exercises", ["exercise_collection_id"], name: "index_exercise_collections_exercises_on_exercise_collection_id", using: :btree
-  add_index "exercise_collections_exercises", ["exercise_id"], name: "index_exercise_collections_exercises_on_exercise_id", using: :btree
-
   create_table "exercise_tags", force: :cascade do |t|
     t.integer "exercise_id"
     t.integer "tag_id"