use the HighCharts lib in Rails by using LazyHighCharts

LazyHighCharts_example.rb

# find the reference here -> http://www.highcharts.com/ref

# github.com/michelson/lazy_high_charts 
require "lazy_high_charts"

class CreateGraph
  
  def init()
    
     mess = []
# -- save me the SUM() of Messages for every day in the last week
     (0..6).each do  |i|
       mess[i] = Message.count(:all, :conditions => ["created_at between ? and ?", (i+1).days.ago, i.days.ago])
      end
    
    message_graph = LazyHighCharts::HighChart.new('graph') do |f| 
      f.options[:chart][:defaultSeriesType] = "area"
      f.title( :text => "Messages in last 7 Days", :style => {:color => "FFF"})
      f.chart( :backgroundColor => '#3F4955' )
# --- the background images wont work
#     f.chart( :plotBackgroundImage => "/images/gb.gif" )
# --- get this shit not to run -> replace it with the giv_me_date() function
#     f.xAxis(:type => 'datetime', :dateTimeLabelFormats => {:day => "%e. %b"}, :labels => {:style => {:color => "FFF"}})
#     f.xAxis(:type => 'datetime', :labels => {:style => {:color => "FFF"}, :formatter  => %|function() {return Highcharts.dateFormat('%d %b %y', this.value );}|.js_code})
      f.xAxis(:categories => giv_me_date , :labels => {:style => {:color => "FFF"}})
      f.yAxis(:title => {:text => "Menge", :style => {:color => "FFF"}}, :labels => {:style => {:color => "FFF"}})
      f.series(:name=>'Messages', :data=> mess) 
      f.legend(:itemStyle => {:color => "FFF"}, :itemHoverStyle => {:color => "FF0F"}, :itemHiddenStyle => {:color => "FFF"}, :borderWidth => nil, :layout => "vertical")
    end

    return message_graph
  end
  
  
  private
 # write this small date function because http://www.highcharts.com/ref/#xAxis--dateTimeLabelFormats will not work
  def giv_me_date
    date = []
    (1..7).each do  |i|
      date[i] = Time.now - (60 * 60 * 24)*(i-1)
      date[i] = date[i].strftime("%d/%m")
    end
   return date.reverse
  end
end


# now create in your controller.rb a Graph object
#    g = CreateGraph.new
#    @message_graph = g.init

# and insert it to your view
#    <%= high_chart("message_chart", @message_graph) %>