Accessing different versions of the Rails Guides
In case you're looking for older versions of the Rails Guides I just created a site with the v2.3.5 ones, besides, if you want to download the guides for the v3.0.0, you will be able to do so as well.
You can download the source code of the site (Sinatra app) from Github:
http://github.com/rafmagana/rails_guides
Mimicking Rails 3’s ActiveRecord query interface in Rails 2.x
NOTICE: This is only for educational and fun purposes, nothing else. I'm not trying to say that you'll get all the pros of the new query interface in Rails 2.x, it isn't even close.
The first time I used the new ActiveRecord query interface (Rails 3) I started to get boring with the one in Rails 2.x, I can't do anything, I have to use the old query interface since converting my projects from Rails 2 to Rails 3 is not an option, so I thought to make a sort of placebo, just for fun, just to be used in my local console, and here is.
module FakeActiveRecord3Methods
def self.included(base)
base.class_eval do
%w/select group order limit offset joins having/.each do |method|
named_scope method.to_sym, lambda { |arg| { method.to_sym => arg } }
end
named_scope :where, lambda { |arg| { :conditions => arg } }
named_scope :includes, lambda { |arg| { :include => arg } }
end
end
end
Click here to see a Gist in GitHub
I used named scopes because they are chainable, if I would have added instance methods to ActiveRecord::Base it would haven't worked as I want to, maybe there's a way to make it work that way, but this was a 5-minutes module, I didn't want to spent too much time on it.
well, I have to say I don't use this module in production servers, only locally in development mode. This is how I configure my development environment to use it:
In my environment/development.rb
config.after_initialize do
[User, And, All, The, Models, You, Want].each do |model|
model.class_eval do
include FakeActiveRecord3Methods
end
end
end
Click here to see a Gist in GitHub
I add the models I use the most, if I need to use the FakeActiveRecord3Methods module in other model I include it in the console. To make this even easier I added to my ~/.irbrc the following code:
class Class
public :include
end
It allows us to include a module this way:
Profile.include FakeActiveRecord3Methods
otherwise Ruby will throw an exception saying we're trying to access a private method.
It might seem cumbersome to make all of this but it isn't that hard.
It's a shame I won't be able to prove that FakeActiveRecord3Methods works in most of the cases but you can test with the examples shown in Rails Guides: Active Record Querying.
Here are some queries using this module anyways. I think all of them are self-explanatory.
User.select("id, email").limit(2)
=> [#<User id: 1, email: "e@mail.com">, #<User id: 2, email: "bar@foo.com">]
User.select("id, email").where(["created_at > ?", 1.month.ago]).order("email DESC").limit(1)
=> [#<User id: 5, email: "foo@bar.com">
User.limit(5) User.select(:id) User.select(:id).limit(10).offset(100) User.order :created_at
Joins
users = User.select("users.id, profiles.company").joins(:profile)
users.first.company # => Foo Company
users.first.profile.company # => Foo Company
Includes
users = User.limit(10) users.first.name # => Foo users.first.profile.company # => it will query the database users = User.includes(:profile).limit(10) # it will bring the profile as well users.first.profile.company # it won't query the database
Of course, you should be aware that in named scopes the order really matters, be careful and remember, in Rails 3, the where, select, group, order, limit, offset, joins and includes returns an instance of ActiveRecord::Relation which is not the case in the FakeActiveRecord3Methods module, it returns an instance of ActiveRecord::NamedScope::Scope and that's because named scopes returns an instance of such class.
Thanks for reading.