DZone Snippets: ruby code

Make a remote URL work like a file upload (in Rails)

seancribbs (Sean Cribbs) — Fri, 11 May 2007 18:04:51 GMT

Want to load a remote URL into an acts_as_attachment/attachment_fu model? Use this little utility class.



  class UrlUpload

    EXTENSIONS = {

      "image/jpeg" => ["jpg", "jpeg", "jpe"],

      "image/gif" => ["gif"],

      "image/png" => ["png"]

    }

    attr_reader :original_filename, :attachment_data

    def initialize(url)

      @attachment_data = open(url)

      @original_filename = determine_filename

    end



    # Pass things like size, content_type, path on to the downloaded file

    def method_missing(symbol, *args)

      if self.attachment_data.respond_to? symbol

        self.attachment_data.send symbol, *args

      else

        super

      end

    end

    

    private

      def determine_filename

        # Grab the path - even though it could be a script and not an actual file

        path = self.attachment_data.base_uri.path

        # Get the filename from the path, make it lowercase to handle those

        # crazy Win32 servers with all-caps extensions

        filename = File.basename(path).downcase

        # If the file extension doesn't match the content type, add it to the end, changing any existing .'s to _

        filename = [filename.gsub(/\./, "_"), EXTENSIONS[self.content_type].first].join(".") unless EXTENSIONS[self.content_type].any? {|ext| filename.ends_with?("." + ext) }

        # Return the result

        filename

      end

  end

Now when you have the URL you want to load, do something like this:



@model.uploaded_data = UrlUpload.new(url)

Or better yet, make a pseudo-accessor on your aaa/attachment_fu model so you can stay "model-heavy".



def url=(value)

  self.uploaded_data = UrlUpload.new(value)

end

Compress your ActiveRecord sessions

seancribbs (Sean Cribbs) — Fri, 27 Apr 2007 16:11:46 GMT

Using ActiveRecordStore and your sessions are getting too big? Try this!



# in environment.rb or some file you require

require 'zlib'

CGI::Session::ActiveRecordStore::Session.class_eval {

  class << self

    def marshal_with_compression(data)

      Zlib::Deflate.deflate(marshal_without_compression(data))

    end

    def unmarshal_with_compression(data)

      unmarshal_without_compression(Zlib::Inflate.inflate(data))

    end

    alias_method_chain :marshal, :compression

    alias_method_chain :unmarshal, :compression

  end

}



# in migration

def self.up

  change_column :sessions, :data, :binary

end



def self.down

  change_column :sessions, :data, :text

end

Turn CSV with headers into Array of Hashes (in 5 lines or less)

seancribbs (Sean Cribbs) — Wed, 25 Apr 2007 15:10:12 GMT

This assumes you have a CSV file whose first line are headings/labels for the individual columns.



require 'csv'



csv_data = CSV.read 'data.csv'

headers = csv_data.shift.map {|i| i.to_s }

string_data = csv_data.map {|row| row.map {|cell| cell.to_s } }

array_of_hashes = string_data.map {|row| Hash[*headers.zip(row).flatten] }

Home-brewed file upload in Ruby on Rails

seancribbs (Sean Cribbs) — Thu, 30 Mar 2006 02:33:29 GMT

Most of this comes from others' work, but I was able to tool it to my needs and fix some bugs. All of these lines go in the model, which for me has a :file and :content_type attributes. :file stores the complete path to the uploaded file. Be sure to change the string in path_to_file to the place where you want files stored, and that proper permissions are set on that path. Also, sanitize_filename doesn't HAVE to be a private method -- make it public if you want.



### Model ###

 def file=(uploaded_file)  

    @uploaded_file = uploaded_file

    @filename = sanitize_filename(@uploaded_file.original_filename)

    write_attribute("content_type", @uploaded_file.content_type)

  end

  

  def after_create

    if !File.exists?(File.dirname(path_to_file))

      Dir.mkdir(File.dirname(path_to_file))

    end

    if @uploaded_file.instance_of?(Tempfile)

      FileUtils.copy(@uploaded_file.local_path, path_to_file)

    else

      File.open(self.path_to_file, "wb") { |f| f.write(@uploaded_file.read) }

    end

    write_attribute("file", path_to_file)

  end



  def after_destroy

    if File.exists?(self.file)

      File.delete(self.file)

      Dir.rmdir(File.dirname(self.file))

    end

  end

  

  def path_to_file

    File.expand_path("#{RAILS_ROOT}/upload/#{self.id}/#{@filename}")

  end

  

  private

  def sanitize_filename(file_name)

    # get only the filename, not the whole path (from IE)

    just_filename = File.basename(file_name) 

    # replace all none alphanumeric, underscore or perioids with underscore

    just_filename.gsub(/[^\w\.\_]/,'_') 

  end

  

### View ###

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