Incompatibility between Rails 1.1.6 and Ruby 1.8.6

After upgrading to Ruby 1.8.6 I discovered a problem with my Rails app (which is still using 1.1.6). Ruby 1.8.6 introduced a changed to the Digest classes. Previously you could use them like:

Digest::SHA1.new("string").digest

This is the way the mysql adapter works in ActiveRecord 1.14.4 (Rails 1.1.6). This no longer valid and will give you this error:

c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/vendor/mysql.rb:551:in `initialize': wrong number of arguments (1 for 0) (ArgumentError)
from c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/vendor/mysql.rb:551:in `new'
from c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/vendor/mysql.rb:551:in `scramble41'
from c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/vendor/mysql.rb:141:in `real_connect'
from c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/connection_adapters/mysql_adapter.rb:330:in `connect'
from c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/connection_adapters/mysql_adapter.rb:87:in `initialize'
from c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/connection_adapters/mysql_adapter.rb:36:in `new'
from c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/connection_adapters/mysql_adapter.rb:36:in `mysql_connection'
from c:/ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/connection_adapters/abstract/connection_specification.rb:251:in `send'

The new Digest constructor takes no parameters. The correct way to use the Digest classes now is:

Digest::SHA1.digest("string")

So what’s the solution? Don’t upgrade to Ruby 1.8.6 until you upgrade to Rails 1.2.x (in which they changed the mysql adapter to use the new syntax). Or, modify the adapter yourself :

ruby/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/active_record/vendor/mysql.rb:552-554

=begin
s1 = Digest::SHA1.new(password).digest
s2 = Digest::SHA1.new(s1).digest
x = Digest::SHA1.new(message + s2).digest
=end

s1 = Digest::SHA1.digest(password)
s2 = Digest::SHA1.digest(s1)
x = Digest::SHA1.digest(message + s2

That’s what I ended up doing.

Alternatively you fix it by putting this little piece of metaprogramming fun somewhere in your environment.rb:

class << Digest::SHA1
  class DigestProxy
    def initialize(content)
      @content = content
    end

    def method_missing(method, *args)
      Digest::SHA1.send(method, @content)
    end
  end

  alias_method :original_new, :new
  def new(*args)
    return original_new  if args.empty?

    DigestProxy.new(args.first)
  end
end