chartkick

1. installation

   # Add this line to your application's Gemfile:
   gem "chartkick" # This is not optional. Without it, function (e.g. line_chart) won't work even if js is ready. 
   # For Rails 6 / Webpacker, run:
   yarn add chartkick chart.js
   # And in app/javascript/packs/application.js, add:
   require("chartkick")
   require("chart.js")
   

2. chart library

   • chart.js
   • Google Charts
   • Highcharts

3. Google chart

   • Load JS <%= javascript_include_tag "https://www.gstatic.com/charts/loader.js" %>
   • Get an API Key
     1. To use google geo_chart, need a API key. (Seems OK for timeline chart).
     2. get a key
     3. AIzaSyCo0AKH9n0-vu92BsU9TwUDKjpmi6c8HZU

   • Set it

     <script type="text/javascript">
     google.charts.load('current', {
     'packages':['geochart'],
     'mapsApiKey': 'AIzaSyCo0AKH9n0-vu92BsU9TwUDKjpmi6c8HZU'
     });
     </script>
     

   • NOTE: I tried to set it in config/initializer/chartkick.rb

     Chartkick.options = {
     language: "en",
     mapsApiKey: "AIzaSyCo0AKH9n0-vu92BsU9TwUDKjpmi6c8HZU", // NOT WORK
     height: "400px", // SEEMS WORK
     colors: ["#b00", "#666"]
     }
     Chartkick.configure({language: "de", mapsApiKey: "..."}) // ERROR to load, no configure function.