ilake ilake

Please note this method is not atomic, it runs first a SELECT, and if there are no results an INSERT is attempted. If there are other threads or processes there is a race condition between both calls and it could be the case that you end up with two similar records.

Whether that is a problem or not depends on the logic of the application, but in the particular case in which rows have a UNIQUE constraint an exception may be raised, just retry:

begin
  CreditAccount.find_or_create_by(user_id: user.id)
rescue ActiveRecord::RecordNotUnique
  retry
end

ujs 會利用到data-type 這個keyword data attributes, 所以當你overwriate 掉時, 你會發現送出的request, header 什麼都不吃accept /, 所以無論你return 什麼他都會看不懂, 當然你預期中的的event (ajax:success) 也不會發生, 會跑到ajax:error 去

<%= form_for @task, :remote => true, :data => {:type => 'casue_problem'} %>

Why We Design

If this application need never change. design does not matter.
In the absence of design, unmanaged dependencies. Changing one object forces change upon its collaborators, which in turn, forces change upon its collaborators, ad infinitum

Judging Design

Easy to change.

How...

Classes with a Single Responsibility
Managing Dependencies

reference

# execute ruby code
instance_eval(File.read(Rails.root.join("config/routes/#{routes_name}.rb")))

# send self be context in the block
self.instance_eval(&block)

# create method
Person.instance_eval do
 # def class_method

The actual rendering is done by subclasses of ActionView::TemplateHandlers.
You can use the :location option to set the HTTP Location header
head :created, location: photo_path(@photo)

# lib/action_dispatch/routing/mapper.rb
# everything under Foo::Application.routes.draw do
# is called by ActionDispatch::Routing::Mapper instance
# The draw method is defined in lib/action_dispatch/routing/route_set.rb
      def draw(&block)
        clear! unless @disable_clear_and_finalize
        eval_block(block)
        finalize! unless @disable_clear_and_finalize
        nil

SimpleDelegator

References

Note

讓自己的class 可以利用include, inherit 得到其他module, class 的能力, 除此之外還可以利用delegate

class A &lt; SimpleDelegator

reference

load

load 了馬上就會進來

autoload

據說要用時才會進來不過經我測試, 在irb 上 ruby-2.0.0-p195, ruby-1.9.3-p392 還是一autload 就進來

	# 單純用來決定該有哪些 interface 和一些是在我們這邊處理的邏輯
	class PaymentGateway
	attr_reader :email

	SUBSCRIPTION_AMOUNT = 10.to_money

	def initialize(user)
	@email = user.email
	end