How to Fix Difference in Behavior of Activesupport 3.0.0 Compare to 2.X

How to fix difference in behavior of activesupport 3.0.0 compare to 2.x?

ActiveSupport no longer loads all its components when you require it. This allows you to cherry-pick the functionality that you want.

require "active_support/core_ext/hash/conversions"
{}.to_xml

Or if you really want all of ActiveSupport:

require "active_support/all"

How can I convert JSON to XML in Ruby?

require 'active_support' #for to_xml() 'gem install activesupport' use the 2.3 branch
require 'json' #part of ruby 1.9 but otherwise 'gem install json'

my_json = "{\"test\":\"b\"}"
my_xml = JSON.parse(my_json).to_xml(:root => :my_root)

Also note the root argument of to_xml. If you don't specify a root it'll use the word 'hash' as the root which isn't very nice to look at.

Got the Phusion Passenger errors with rails

I have already got solution. When I have check which passenger , I found there are 2 place that may cause some conflict problem. Because of the previous command there:

• sudo gem install passenger
• gem install passenger

then i do

• sudo gem uninstall passenger
• gem uninstall passenger

and do

• gem install passenger
• passenger-install-apache2-module

and I got my application back .

`method_missing': undefined method `devise' for User (call 'User.connection' to establish a connection)

This happens because you missed the command:

rails generate devise:install

You need just comment all devise lines temporally (in routes.rb / user.rb) to not get raise.

And run command again.

Ruby on Rails: alias_method_chain, what exactly does it do?

1 - is it still used at all?

Apparently yes, alias_method_chain() is still used in Rails (as of version 3.0.0).

2 - when would you use
alias_method_chain and why?

(Note: the following is largely based on the discussion of alias_method_chain() in Metaprogramming Ruby by Paolo Perrotta, which is an excellent book that you should get your hands on.)

Let's start with a basic example:

class Klass
  def salute
    puts "Aloha!"
  end
end

Klass.new.salute # => Aloha!

Now suppose that we want to surround Klass#salute() with logging behavior. We can do that what Perrotta calls an around alias:

class Klass
  def salute_with_log
    puts "Calling method..."
    salute_without_log
    puts "...Method called"
  end

  alias_method :salute_without_log, :salute
  alias_method :salute, :salute_with_log
end

Klass.new.salute
# Prints the following:
# Calling method...
# Aloha!
# ...Method called

We defined a new method called salute_with_log() and aliased it to salute(). The code that used to call salute() still works, but it gets the new logging behavior as well. We also defined an alias to the original salute(), so we can still salute without logging:

Klass.new.salute_without_log # => Aloha!

So, salute() is now called salute_without_log(). If we want logging, we can call either salute_with_log() or salute(), which are aliases of the same method. Confused? Good!

According to Perrotta, this kind of around alias is very common in Rails:

Look at another example of Rails
solving a problem its own way. A few
versions ago, the Rails code contained
many instances of the same idiom: an
Around Alias (155) was used to add a
feature to a method, and the old
version of the method was renamed to
something like
method_without_feature(). Apart from
the method names, which changed every
time, the code that did this was
always the same, duplicated all over
the place. In most languages, you
cannot avoid that kind of duplication.
In Ruby, you can sprinkle some
metaprogramming magic over your
pattern and extract it into its own
method... and thus was born
alias_method_chain().

In other words, you provide the original method, foo(), and the enhanced method, foo_with_feature(), and you end up with three methods: foo(), foo_with_feature(), and foo_without_feature(). The first two include the feature, while the third doesn't. Instead of duplicating these aliases all around, alias_method_chain() provided by ActiveSupport does all the aliasing for you.

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