How to Create Zip File Only in Memory in Ruby

How can I generate zip file without saving to the disk with Ruby?

I had a similar problem which I solved using the rubyzip gem and the stringio object.
It turns out that rubyzip provides a method that returns a stringio object: ZipOutputStream.write_buffer.

You can create the zip file structure as you like using put_next_entry and write and once you are finished you can rewind the stringio and read the binary data using sysread.

See the following simple example (works for rubyzip 0.9.X)

require 'zip/zip'
stringio = Zip::OutputStream.write_buffer do |zio|
  zio.put_next_entry("test.txt")
  zio.write "Hello world!"
end
stringio.rewind
binary_data = stringio.sysread

Tested on jruby 1.6.5.1 (ruby-1.9.2-p136) (2011-12-27 1bf37c2) (Java HotSpot(TM) 64-Bit Server VM 1.6.0_29) [Windows Server 2008-amd64-java])

The following example works for rubyzip >= 1.0.0

require 'rubygems'    
require 'zip'
stringio = Zip::OutputStream.write_buffer do |zio|
  zio.put_next_entry("test.txt")
  zio.write "Hello world!"
end
binary_data = stringio.string

Tested on jruby 1.7.22 (1.9.3p551) 2015-08-20 c28f492 on OpenJDK 64-Bit Server VM 1.7.0_79-b14 +jit [linux-amd64] and rubyzip gem 1.1.7

How can I create a zip file without temporary files in ruby?

See the answer at "How can I generate zip file without saving to the disk with Ruby?"

I adapted your example to demonstrate it works.

require 'zip/zip'

zipname = 'test.zip'
File.delete(zipname) if File.exists?(zipname) #delete previous version

stringio = Zip::ZipOutputStream::write_buffer do |zio|
  1.upto(5) do |i| #Just some testfiles with content
    zio.put_next_entry("test#{i}.txt") #Filename
    zio.write("Testcontent %08i" % i)  #generated content
    sleep 1 #sleep some time to see the temporary files
  end
end
stringio.rewind #reposition buffer pointer to the beginning
File.new("test.zip","wb").write(stringio.sysread) #write buffer to zipfile

How to iterate through an in-memory zip file in Ruby

See @bronson’s answer for a more up to date version of this answer using the newer RubyZip API.

The Rubyzip docs you linked to look a bit old. The latest release (0.9.9) can handle IO objects, so you can use a StringIO (with a little tweaking).

Even though the api will accept an IO, it still seems to assumes it’s a file and tries to call path on it, so first monkey patch StringIO to add a path method (it doesn’t need to actually do anything):

require 'stringio'
class StringIO
  def path
  end
end

Then you can do something like:

require 'zip/zip'
Zip::ZipInputStream.open_buffer(StringIO.new(last_response.body)) do |io|
  while (entry = io.get_next_entry)
    # deal with your zip contents here, e.g.
    puts "Contents of #{entry.name}: '#{io.read}'"
  end
end

and everything will be done in memory.

Create in-memory only gzip

You're actually gzipping normal.to_s(which is something like "#<File:0x007f53c9b55b48>") in the following code.

# Files
normal = File.new('chunk0.nbt')

# Try to create gzip in program
make_gzip normal

You should read the content of the file, and make_gzip on the content:

make_gzip normal.read

As I commented, the make_gzip can be updated:

def self.make_gzip(data)
  gz = Zlib::GzipWriter.new(StringIO.new)
  gz << data
  gz.close.string
end

Processing Zip files in Ruby

Hi I'm using rubyzip library. You can do something like this:

Zip::ZipFile.foreach(file) do |entry|
    istream = entry.get_input_stream
    data = istream.read
    #...
end

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