如何在Ruby中通过电子邮件发送图表而不保存到磁盘？

为简单起见,它使用纯Ruby PNG图;真实世界的应用程序可能会使用SVG,快速本机代码或图形API.

#!/usr/bin/env ruby
=begin

How to send a graph via email in Ruby without saving to disk
Example code by Joel Parker Henderson at SixArm,joel@sixarm.com

    https://stackoverflow.com/questions/9779565

You need two gems:

    gem install chunky_png
    gem install mail

Documentation:

    http://rdoc.info/gems/chunky_png/frames
    https://github.com/mikel/mail

=end


# Create a simple PNG image from scratch with an x-axis and y-axis.
# We use ChunkyPNG because it's pure Ruby and easy to write results;
# a real-world app would more likely use an SVG library or graph API.

require 'chunky_png'
png = ChunkyPNG::Image.new(100,100,ChunkyPNG::Color::WHITE)
png.line(0,50,ChunkyPNG::Color::BLACK)  # x-axis
png.line(50,ChunkyPNG::Color::BLACK)  # y-axis

# We do IO to a String in memory,rather than to a File on disk.
# Ruby does this by using the StringIO class which akin to a stream.
# For more on using a string as a file in Ruby,see this blog post:
# http://macdevelopertips.com/ruby/using-a-string-as-a-file-in-ruby.html

io = StringIO.new
png.write(io) 
io.rewind

# Create a mail message using the Ruby mail gem as usual. 
# We create it item by item; you may prefer to create it in a block.

require 'mail'
mail = Mail.new
mail.to = 'alice@example.com'
mail.from = 'bob@example.com'
mail.subject = 'Hello World'

# Attach the PNG graph,set the correct mime type,and read from the StringIO

mail.attachments['graph.png'] = {
  :mime_type => 'image/png',:content => io.read 
}

# Send mail as usual. We choose sendmail because it bypasses the OpenSSL error.
mail.delivery_method :sendmail
mail.deliver