Overview

I had to create a lot of zip files for a certain task, but I was saved by encountering this gem. This article introduces four ways to work with zip files using ruby.

Ruby version

Ruby 2.4 or higher

install gem

Add to Gemfile

`Gemfile`


gem 'rubyzip'

Run the following command in the terminal

`terminal`


bundle install

Use properly for 4 purposes

1. Create a zip file

Zip::OutputStream.open('example.zip') do |zos|
  zos.put_next_entry('first_file.txt')
  zos.puts 'hoge hoge'

  zos.put_next_entry('second_file.txt')
  zos.puts 'hoge again'
end

Use a string or the data read from the file as an argument to the puts method. The contents of the generated zip file have the following structure.

example.zip
- first_file.txt
- second_file.txt

The contents of each file are as follows.

`first_file.txt`


hoge hoge

`second_file.txt`


hoge again

2. Read the zip file

The files in the zip file are set one after another by the get_next_entry method.

Zip::InputStream.open('example.zip') do |zis|
  entry = zis.get_next_entry
  print "First line of '#{entry.name} (#{entry.size} bytes):  "
  puts "'#{zis.gets.chomp}'"
  entry = zis.get_next_entry
  print "First line of '#{entry.name} (#{entry.size} bytes):  "
  puts "'#{zis.gets.chomp}'"
end

If you read the ʻexample.zip` generated in ** 1 **, you will see the following.

`terminal`


First line of 'first_file.txt (10 bytes):  hoge hoge
First line of 'second_file.txt (11 bytes):  hoge again

3. Read the zip file directory

Use the get_input_stream (entry) method to get the ʻInputStream` for each entry.

zf = Zip::File.new('example.zip')
zf.each_with_index do |entry, index|
  puts "entry #{index} is #{entry.name}, size = #{entry.size}, compressed size = #{entry.compressed_size}"
end

This source code displays the compressed files ʻindex, name, size, compressed_size` in a zip file.

If you read the ʻexample.zip` generated in ** 1 **, you will see the following.

`terminal`


entry 0 is first_file.txt, size = 10, compressed size = 10
entry 1 is second_file.txt, size = 11, compressed size = 13

4. Modify the zip file

Modify the zip file directly

Add the file indicated by path with ʻadd (entry, path) Rename withrename (entry, new_name)`

Modify the file generated by ** 1 **

Zip::File.open('example.zip') do |zip_file|
  zip_file.add('third_file.txt', 'third_file.txt')
  zip_file.rename('first_file.txt', 'first_file_rename.txt')
  zip_file.add('fourth_file.txt', 'fourth_file.txt')
end

The following files are additionally prepared.

`third_file`


hoge third

`fourth_file`


hogehoge fourth

I will try it. Get information using ** 3 **

`terminal`


entry 0 is second_file.txt, size = 11, compressed size = 13
entry 1 is third_file.txt, size = 10, compressed size = 12
entry 2 is first_file_rename.txt, size = 10, compressed size = 10
entry 3 is fourth_file.txt, size = 14, compressed size = 14

The generated zip file has been modified to have the following structure:

example.zip
- second_file_txt
- third_file.txt
- first_file_rename.txt
- fourth_file.txt

Summary

In this article, I have introduced four ways to work with zip files. There are other useful methods in rubyzip, so it is recommended to take a look.