fileconv

Fileconv

Extensible multi-file convertor. Simple text file, CSV file, JSON file, binary file and so on.

fileconv gem is a simple to use and extensible library to convert multi-file format. You can extend your class with MetaConvertor and convert files into various format.

Installation

Add this line to your application's Gemfile:

gem 'fileconv'

And then execute:

$ bundle

Or install it yourself as:

$ gem install fileconv

Usage

You have to do a few things to build a Convertor with fileconv gem.

• include MetaConvertor(e.g. Fileconv::Line) into your object,
• add some hooks(e.g. input_ext) if you need.

Lets start with a simple example. It will be a convertor for simple text files.

require 'fileconv'

class AddLinenoConvertor
  include Fileconv::Line
  def input_ext
    "txt"
  end

  def init_acc(acc)
    acc[:lineno] = 0
  end

  def convert_line(line, acc)
    acc[:lineno] += 1
    "#{acc[:lineno]}: #{line}"
  end
end

That's it. Now you can use a method #conv to convert all text files(.txt) from into text files with line number.

convertor = AddLinenoConvertor.new
convertor.conv

If you have two text(.txt) files:

aaa.txt

aaa
bbb
ccc

bbb.txt

111
222
333

the convertor convert it into:

output/aaa.txt

1: aaa
2: bbb
3: ccc

output/bbb.txt

1: 111
2: 222
3: 333

Convertor Hooks

You can overwrite convertor hooks if you need. The default action is that a converter copies all files in the current directory to an “output” directory. The convertor make the "output" directory in the current directory if it doesn't exist.

hook	default	description
input_dir	"."(current directory)	input Directory
input_ext	nil (all files)	input extension
output_dir	"output"	output directory
input_files(files)	files	input files
init_conv	nil	init convertor hook
init_acc(acc)	nil	init accumulator hook
read_file(filename, acc)	nil (use default reader)	read file hook
convert_line(line, acc)	line	convert line hook
convert_file(file, acc)	file	convert file hook
output_filename(filename, acc)	filename	output filename
result_filename	"result.txt"	result filename
conv_result	nil	conversion result

Input files is selected by input_dir and input_ext. you can overwrite it with #input_files hooks.

The most commonly used hooks are：

• #input_ext
• #convert_line
• #convert_file
• #conv_result

Convertor Variables

You can use several convertor variables. Convertor variables are Hash type and have a specific scope. acc has single file scope, which means that it is initialized for each file. @meta and @opts is valid in a convertor. @opts variable is set by #conv method that takes user options. you can use @meta variable for any purpose.

variable	scope	descripton
acc	file	accumulator for a file
@meta	convertor	meta data for the convertor
@opts	convertor	options for the convertor

Default MetaConvertors

fileconv gem have several default MetaConvertors. MetaConverters are mainly intended to be included by a converter.

MetaConvertor	mode	description
Line	Line	get raw line data
CSV	Line	get a CSV line(Array or Row)
Data	File	get raw file data
File	File	get a File object
Stat	File	get a Stat object
JSON	File	get a JSON object

Convertors(includes MetaConvertors) can be divided into two modes.

• Line Mode
  • #convert_line hook is called.
  • #convert_file hook is called.
  • e.g. Line, CSV
• File Mode
  • #convert_line hook is not called.
  • #convert_file hook is called.
  • e.g. Data, File, Stat, JSON

Let's see a JSON MetaConvertor usage.

require 'fileconv'

class ModifyJSONConvertor
  include Fileconv::JSON

  def input_ext
    "json"
  end

  def convert_file(data, acc)
    data.map do |e|
      e["country"] = "USA"
      e
    end
  end
end

ModifyJSONConvertor.new.conv

original file (address.json) :

[{"name": "Mike", "Age": "21"}, {"name": "Jon", "Age": "33"}]

converted file (output/address.json) :

[{"name":"Mike","Age":"21","country":"USA"},{"name":"Jon","Age":"33","country":"USA"}]

You can see more examples.

Make MetaConvertors

You can make meta convertors easily. fileconv gem's JSON MetaConvertor is below:

require "json"

module Fileconv
  module JSON
    include Fileconv::Base

    def pre_init_conv
      @opts[:read_json_opts] ||= {}
      @opts[:write_json_opts] ||= {}
    end

    def pre_convert_file(data, acc)
      ::JSON.parse(data, @opts[:read_json_opts])
    end

    def post_convert_file(obj, acc)
      return unless obj
      if @opts[:pretty_json]
        ::JSON.pretty_generate(obj, @opts[:write_json_opts])
      else
        ::JSON.generate(obj, @opts[:write_json_opts])
      end
    end
  end
end

MetaConvertors can use below hooks:

• pre_init_conv
• post_init_conv
• pre_input_files
• post_input_files
• pre_init_acc
• post_init_acc
• pre_convert_file
• pre_convert_line
• post_convert_line
• post_convert_file
• pre_conv_result
• post_conv_result

Development

After checking out the repo, run bin/setup to install dependencies. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/hinastory/fileconv.

License

The gem is available as open source under the terms of the MIT License.