Deal with CORS in a less hacky way

schedules_api/Gemfile

@@ -53,7 +53,7 @@ end
 gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
 
 gem 'httparty'
+gem 'icalendar'
 gem 'nokogiri'
+gem 'rack-cors', require: 'rack/cors'
 gem 'rubyXL'
-
-gem 'icalendar'

schedules_api/Gemfile.lock

@@ -96,6 +96,7 @@ GEM
     public_suffix (3.0.2)
     puma (3.11.3)
     rack (2.0.4)
+    rack-cors (1.0.2)
     rack-test (1.0.0)
       rack (>= 1.0, < 3)
     rails (5.1.6)
@@ -193,6 +194,7 @@ DEPENDENCIES
   pry
   pry-doc
   puma (~> 3.7)
+  rack-cors
   rails (~> 5.1.6)
   rubyXL
   sass-rails (~> 5.0)

schedules_api/app/controllers/calendar_generator_controller.rb

@@ -4,9 +4,8 @@ require 'time'
 class CalendarGeneratorController < ApplicationController
   def generate
     cal = Icalendar::Calendar.new
-    posted_crns = JSON.parse(request.body.read)
 
-    posted_crns.each do |crn|
+    params[:_json].each do |crn|
       section = Section.find_by_crn(crn)
       event = generate_event_from_section(section)
       cal.add_event(event)

schedules_api/config/application.rb

@@ -14,8 +14,13 @@ module Schedules
     # Settings in config/environments/* take precedence over those specified here.
     # Application configuration should go into files in config/initializers
     # -- all .rb files in that directory are automatically loaded.
-    config.action_dispatch.default_headers = {
-      'Access-Control-Allow-Origin' => '*'
-    }
+
+    # allow GET, POST or OPTIONS requests from any origin on any resource
+    config.middleware.insert_before 0, Rack::Cors do
+      allow do
+        origins '*'
+        resource '*', :headers => :any, :methods => [:get, :post, :options]
+      end
+    end
   end
 end

schedules_web/src/components/App.tsx

@@ -32,20 +32,23 @@ class App extends React.Component<any, State> {
     }
 
     addSectionToCurrentScheduleIfUnique = (section: Section) => {
-        if (!this.state.currentSchedule.find(sectionInSchedule => section === sectionInSchedule)) {
+        if (!this.isSectionInSchedule(section)) {
             this.setState({
                 currentSchedule: [...this.state.currentSchedule, section],
             });
         }
     };
 
+    isSectionInSchedule = (section: Section) =>
+        this.state.currentSchedule.find(sectionInSchedule => section === sectionInSchedule);
+
     generateSchedule = () => {
         const crns = this.state.currentSchedule.map(section => section.crn);
         fetch('http://localhost:3000/api/generate', {
             method: 'POST',
             body: JSON.stringify(crns),
             headers: {
-                'Content-Type': 'text/plain',
+                'Content-Type': 'application/json',
             },
         })
             .then(response => response.text())