Undeletes a document from a CouchDB database.

couchdb-undelete.rb

#!/usr/bin/env ruby
#
# Undelete a document from a CouchDB database.
#
# Recovers a previously deleted document by looking at the _changes
# feed, putting a new empty document preserving the revisions chain,
# retrieves the revs_info for the document, asks the user which one
# to recover, and puts back the old revision into place.
#
# For this to work, GETting the document must return error: "not_found",
# deleted: true.
#
# Requires Typhoeus and Oj.
#
# Latest version: https://gist.github.com/vjt/6158675
#
# h/t to http://stackoverflow.com/questions/10854883/retrieve-just-deleted-document
#
#  - vjt  Mon Aug  5 21:22:13 CEST 2013
#
# Made in Ventotene.
#
require 'typhoeus'
require 'oj'

def get(url, params = {})
  res = Typhoeus.get(url, :params => params, :headers => {'Accept' => 'application/json'})
  Oj.load(res.body)
end

def put(url, body, params = {})
  res = Typhoeus.put(url, :body => Oj.dump(body), :params => params, :headers => {'Accept' => 'application/json'})
  Oj.load(res.body)
end

def delete(url, params = {})
  res = Typhoeus.delete(url, :params => params, :headers => {'Accept' => 'application/json'})
  Oj.load(res.body)
end

class UndeleteError < StandardError; end

if $0 == __FILE__

database = ARGV[0]
docid    = ARGV[1]
unless database && docid
  raise ArgumentError, "Usage: #$0 <Database> <Document ID>"
end

docurl = [database, docid].join('/')
changes = [database, '_changes'].join('/')
puts "Processing document #{docurl}..."

# Verify the document is deleted
res = get(docurl)
unless res == {"error"=>"not_found", "reason"=>"deleted"}
  raise UndeleteError, "The specified document is not recoverable. Sorry, you'll have to recover from backup."
end

# Now get the last revision from _changes
res = get(changes)['results'].select {|d| d['id'] == docid && d['deleted'] == true}.last
unless res
  raise UndeleteError, "Could not find the last delete change."
end

lastrev = res['changes'].first['rev']

# Put a new empty_version of the document
res = put(docurl, {}, {:rev => lastrev})
unless res['ok'] == true
  raise UndeleteError, "Sorry, an unexpected error has occurred: #{res.inspect}"
end

currrev = res['rev']

# Show previous revisions
res = get(docurl, :revs_info => true)
puts "The following revisions have been found:"
puts res['_revs_info'].select {|r| r['status'] == 'available'}.map(&:inspect).tap(&:shift).join("\n")

print "Type the revision number you want to recover: "
rev = $stdin.gets.chomp

puts "OK, fetching revision #{rev}..."
recovered = get(docurl, :rev => rev, :attachments => true)
recovered['_rev'] = currrev

puts "Putting back the document into couchdb..."
res = put docurl, recovered, :rev => currrev

if res['ok'] == true
  puts "All done. Check that #{docurl} now contains what you do expect."
else
  puts "An error occurred: #{res}"
end

end # if $0 == __FILE__

# EOF