Store the selected talks as associated records

app/assets/javascripts/halfnarp.js

@@ -41,7 +41,9 @@
             }
 
             /* Convert preferences to JSON and post them to backend */
-            var request = {talk_preference: {'talks': ids}};
+            var request = {talk_preference: {'selected_talks_attributes': ids.map(function(talk_id) {
+                return {"talk_id": talk_id};
+            })}};
             if( !myapi || !myapi.length ) {
                 /* If we do not have resource URL, post data and get resource */
                 $.post( halfnarpAPI, request, function( data ) {

app/controllers/talk_preferences_controller.rb

@@ -26,20 +26,25 @@ class TalkPreferencesController < ApplicationController
   def update
     @talk_preference = TalkPreference.find params[:id]
 
-    if @talk_preference.update talk_preference_params
-      render json: {
-               update_url: talk_preference_url(@talk_preference),
-               hashed_uid: @talk_preference.hashed_unique_id,
-               uid: @talk_preference.id
-             }
-    else
-      render status: :unprocessable_entity
+    @talk_preference.transaction do
+      @talk_preference.selected_talks.destroy_all
+
+      if @talk_preference.update talk_preference_params
+        render json: {
+                      update_url: talk_preference_url(@talk_preference),
+                      hashed_uid: @talk_preference.hashed_unique_id,
+                      uid: @talk_preference.id
+                     }
+      else
+        head :unprocessable_entity
+        raise ActiveRecord::Rollback
+      end
     end
   end
 
   private
 
   def talk_preference_params
-    params.require(:talk_preference).permit(talks: [])
+    params.require(:talk_preference).permit(selected_talks_attributes: [:talk_id])
   end
 end

app/models/talk_preference.rb

@@ -1,7 +1,7 @@
 class TalkPreference < ActiveRecord::Base
-  has_many :selected_talks
-
   self.primary_key = :unique_id
+  has_many :selected_talks
+  accepts_nested_attributes_for :selected_talks
 
   before_create :assign_new_unique_id