title: Begin and Rescue block exception handling
body: <p>I have little experience in rails exception handling. I have this snippet</p>
  
  <pre><code>def update
    @game = Game.find(params[:id])
    begin
      params[:game][:tier] = eval(params[:game][:tier]) 
    rescue 
      @game.errors.add(:tier, "Please make sure the correct format for tier, example [100, 1000, 10000]")
    end
  #.... more code
  end
  </code></pre>
  
  <p>In case params[:game][:tier] = "[100,200]" everything is perfect.
  In case of error case of ruby syntax like params[:game][:tier] = "[100,200] abc" it catch the error however the application just crush.</p>
  
  <p>How can I handle exception with 'eval()' such that it won't crush the app? Why begin and rescue does not work in this case? Appreciate any help for ruby enlightenment thanks :)</p>