ruby - 如何在 Ruby 中通过电子邮件发送图表而不保存到磁盘？

Question

我正在使用 Ruby 脚本和“邮件”gem 发送电子邮件。

问题 - 如何在 Ruby 中通过电子邮件发送图表而不保存到磁盘？这可能吗？您会推荐哪种绘图工具，“邮件”gem 是否支持以某种方式将其输出？（或者它必须先保存到磁盘）如果可能/简单的示例代码行应该如何会很棒......

Answer 1

你的完整答案。

为简单起见，它使用纯 Ruby PNG 图；现实世界的应用程序可能会使用 SVG、快速的原生代码或图形 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

    http://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, 100, 50, ChunkyPNG::Color::BLACK)  # x-axis
png.line(50, 0, 50, 100, 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

Answer 2

我不明白你为什么不能。在邮件的文档中，您可以看到以下示例代码：

mail = Mail.new do
  from     'me@test.lindsaar.net'
  to       'you@test.lindsaar.net'
  subject  'Here is the image you wanted'
  body     File.read('body.txt')
  add_file :filename => 'somefile.png', :content => File.read('/somefile.png')
end

mail.deliver!

您只需要将目标替换:content => ...为内存中的文件内容。这应该足够了。没有必要将附件保存（即使是临时保存）到磁盘，因为它们在 base64 中重新编码并添加到邮件末尾。

对于您问题的第二部分，那里有很多绘图/图形库。例如，请参阅此问题或此库。

对于这类事情，实际上并没有一个高于其他库的库。有许多不同用途的库，您必须选择更适合您的需求和约束的库。