Rails 3 的active record和其他

今天，徘徊在几个问题之间简单流水帐，复制一下

现在的Rails版本是3.0.7
看active record呢

http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html
http://api.rubyonrails.org/classes/ActiveRecord/Base.html

上面的官网API看起来很不错
之前版本如下

http://ar.rubyonrails.org/classes/ActiveRecord/Base.html

Company.where(
  "id = :id AND name = :name AND division = :division AND created_at > :accounting_date",
  { :id => 3, :name => "37signals", :division => "First", :accounting_date => '2005-01-01' }
).first

Student.where(:first_name => "Harvey", :status => 1)
Student.where(params[:student])

User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }]) do |u|
  u.is_admin = false
end

Post.find_by_sql ["SELECT title FROM posts WHERE author = ? AND created > ?", author_id, start_date]
> [#<Post:0x36bff9c @attributes={"first_name"=>"The Cheap Man Buys Twice"}>, ...]

关于relation

TreeMixin.find :all, :joins => :children
# => SELECT ... FROM mixins INNER JOIN mixins childrens_mixins ...
TreeMixin.find :all, :joins => {:children => :parent}
# => SELECT ... FROM mixins INNER JOIN mixins childrens_mixins ...
                            INNER JOIN parents_mixins ...
TreeMixin.find :all, :joins => {:children => {:parent => :children}}
# => SELECT ... FROM mixins INNER JOIN mixins childrens_mixins ...
                            INNER JOIN parents_mixins ...
                            INNER JOIN mixins childrens_mixins_2

在rails 3下卸载active record

引用

The rails command that generates the application template now has an option -O, which tells it to skip ActiveRecord.

If you don't feel like rerunning rails, you should check the following in your existing app:

    Check that your config/application.rb doesn't have require 'rails/all' or require "active_record/railtie". Instead, for a standard Rails setup without ActiveRecord, it should have only the following requires:

    require File.expand_path('../boot', __FILE__)


    require "action_controller/railtie"
    require "action_mailer/railtie"
    require "active_resource/railtie"
    require "rails/test_unit/railtie"


    # Auto-require default libraries and those for the current Rails environment.
    Bundler.require :default, Rails.env

    If, in config/application.rb, you are using the config.generators section, make sure it doesn't have the line g.orm :active_record. You can set this explicitly to nil, if you want, but this should be the default when g.orm is completely omitted.

    Optional, but in your Gemfile, remove the gem line that loads the module for your database. This could be the line gem "mysql" for example.