convert html img tags to rails image_tag calls

img_convert.rb

#!/usr/bin/env ruby
require "nokogiri"

# opens every file in the given dir tree and converts any html img tags to rails image_tag calls
#
# example usage: 
# ruby convert.rb ~/my_rails_app/app/views
#
# ***be careful and backup before using this***
#

raise "no directory tree given" if ARGV.first.nil?

path = "#{ARGV.first}/**/*"

@count = {
  :files_open => 0,
  :files_revised => 0,
  :tags => 0
}

class RailsImageTag
  
  Params = [
    { :name => :alt }, 
    { :name => :height, :type => :int },
    { :name => :width, :type => :int } 
  ]
  
  def initialize(img)
    @img = img
  end
  
  # construct and return the erb containing the new image_tag call
  def to_erb
    url = @img['src']
    #url.gsub!("/images/", "")
    #url.gsub!("images/", "")
    "<%= image_tag('#{url}'#{options_to_erb}) %>"
  end
  
  # convert the img tag params to image_tag options
  # the params to process are defined in the Params constant hash
  def options_to_erb
    options_erb = {}
    Params.each do |opt|
      name = opt[:name]
      value = @img[name]
      value = opt[:type] != :int ? "'#{value}'" : value
      options_erb[name] = ":#{name} => #{value}"
    end
    options_erb.empty? ? "" : ", " + options_erb.values.join(", ") 
  end
  
end

class HtmlDoc
  
  def initialize(filename)
    @name = filename
    file = File.open(@name)
    @doc = Nokogiri::HTML(file)
    @content = File.open(@name) { |f| f.read }
  end
  
  # overwrite the file with new contents
  def write_file(log)
    log[:files_revised] += 1
    File.open(@name, "w") {|f| f.write(@content) }
  end
  
  # convert a single file and record stats to <em>log</em>
  def convert_img_tags!(log)
    log[:files_open] += 1
    file_marked = false
    @doc.xpath("//img").each do |img| 
      file_marked = true
      log[:tags] += 1
      original = img.to_html.gsub("\">", "\" />").gsub("\" >", "\" />").delete("\\")
      @content.gsub!(original, RailsImageTag.new(img).to_erb)
    end
    write_file(log) if file_marked
  end
  
end

Dir.glob(path).each { |filename| HtmlDoc.new(filename).convert_img_tags!(@count) if File.file?(filename) }

p "***********************************"
p "#{@count[:files_open]} files opened"
p "#{@count[:files_revised]} files revised"
p "#{@count[:tags]} tags replaced"

Your script was incredibly useful in porting a bunch of large templates to Rails (I also modified it to replace <a> tags with link_to), but it never seemed to work until I commented out everything after to_html on line 79. Presumably it's because the gsubbed original no longer matched what was actually in the page. I'm not sure what that line is meant to do, but if anyone is having trouble getting this to work, you'll probably need to do what I did.

I think there is a mistake on line 79. It works for me if I remove a space. Here's what I change:

 original = img.to_html.gsub("\">", "\" />").gsub("\" >", "\" />").delete("\\")
 original = img.to_html.gsub("\">", "\"/>").gsub("\" >", "\" />").delete("\\")

The problem is nokogiri 's img tag.to_html function does not necessarily give you the same string as the in your file. It returns "" when your original HTML is ""

So depending on how your tags are written in the HTML, you might need to play around with line 79 so that the substitution is able to find the original string.

Also, the options_to_erb function and params variable makes certain assumptions that cause problems for your img attributes:

1. that you always have a width attribute
   2 that height and width are just integers rather than strings
2. that alt, height, width are the only attributes your image has

Great gist. Helped me a lot.

I just changed the line 79, like @KevinVerre said, and because I had class at my html template, I change:
Params = [ { :name => :alt }, { :name => :height, :type => :int }, { :name => :width, :type => :int } ]

for:
Params = [ { :name => :class } ]