如何在Ruby中给定URL中的base64编码媒体

Question

I'm trying to upload an image to PingFM. Their documentation says:

media – base64 encoded media data.

I can access this image via the URL. I tried (practically guessed) this:

ActiveSupport::Base64.encode64(open("http://image.com/img.jpg"))

But I get this error:

TypeError: can't convert Tempfile into String
    from /usr/lib/ruby/1.8/base64.rb:97:in `pack'
    from /usr/lib/ruby/1.8/base64.rb:97:in `encode64'
    from (irb):19
    from :0

Answer 1

To encode a file:

require 'base64'
Base64.encode64(File.open("file_path", "rb").read)

To produce the file from the encoded string:

require 'base64'
encoded_string = Base64.encode64(File.open("file_path", "rb").read)

File.open(file_name_to_create, "wb") do |file|
    file.write(Base64.decode64(encoded_string))
end

Answer 2

The open method:

open("http://image.com/img.jpg")

is returning a Tempfile object, while encode64 expects a String.

Calling read on the tempfile should do the trick:

ActiveSupport::Base64.encode64(open("http://image.com/img.jpg") { |io| io.read })

Answer 3

This will work too, it's a little cleaner

 require 'base64'

 Base64.encode64(open("file_path").to_a.join)

"How do you decode this back into a file?" - @user94154

 require 'base64'

 open('output_file_name.txt', 'w') do |f| 
   f << Base64.decode64( encoded_content )
 end

Where encoded_content would be the previously encoded file content return value.

Answer 4

Encode a file to base64 encoding:

File.open("output_file","w"){|file| file.write [open("link_to_file").string].pack("m")}

Decode base64 encoded file:

File.open('original', 'wb') {|file| file << (IO.readlines('output_file').to_s.unpack('m')).first }

Answer 5

Here's my solution:

1: Put this custom image_tag method into ApplicationHelper, and include ActiveSupport module

module ApplicationHelper
  include ActiveSupport
  def image_tag_base64(file_path, mime_type = 'image/jpeg', options = {})
    image_tag("data:#{mime_type};base64,#{Base64.encode64(open(file_path) { |io| io.read })}", options)
  end
end

2: Then, inside the view you want to use base64 encoded image use the method like this:

<%= image_tag_base64 @model.paperclip_attribute.path(:size), @model.paperclip_attribute.content_type, {class: 'responsive-img etc etc'} %>

3: DONE

Answer 6

In case it's useful to others, here's how to save a screenshot as base64 using Watir

browser = Watir::Browser.new(:chrome, {:chromeOptions => {:args => ['--headless', '--window-size=1000x1000']}})
browser.goto("http://www.yourimage.com")
browser.screenshot.base64

The beauty of this is you don't need to store the image itself