Learning note of "Agile web development with Rails 5" book

Learning note of "Agile web development with Rails 5" book.txt

<< Agile web development with Rails 5 >>

<< Notes >>

< Gems documentation server >
1. run "gem server"
2. open "localhost:8808"

< VM for RoR core development >
$ git clone https://github.com/rails/rails-dev-box.git
$ cd rails-dev-box
$ vagrant up

< Description of a Project >

1. run "rails about"

< Enabling rails to be accessible in local network >

1. run "rails s -b 0.0.0.0

< Undo and reapply last migration >

1. run "rails db:migrate:redo"

< Caching in dev environment >

1. run 'rails dev:cache'
2. <% cache @products do %>
	<% @products.each do |product| %>
		<% cache product do %>
			<div class="entry">
			<%= image_tag(product.image_url) %>
			<h3><%= product.title %></h3>
			<%= sanitize(product.description) %>
			<div class="price_line">
			<span class="price"><%= number_to_currency(product.price) %></span>
			</div>
			</div>

		<% end %>
	<% end %>
   <% end %>

< Rails db:migrate with status >
1. run 'rails db:migrate:status'


< Rails controller error logger >

1. Use the Rails logger to record the error. Every controller has a logger attribute. Here we use it to record a message at the error logging level.

2. Code 'logger.error "Attempt to access invalid cart #{params[:id]}"'

< Clear logs from Rails >
1. run 'rails log:clear LOGS=development'

< Summing column's values using Rails's sum method >
1. line_items.to_a.sum{ |item| item.total_price }
2. line_items.sum(&:total_price)


<< Rails's components >>

< Load anything from 'lib' folders >
- Add following code in 'config/application.rb'
> config.autoload_paths += %W(#{Rails.root}/lib)

< A Place for Script Wrappers >
- the bin directory is the place to put wrappers that call scripts that are launched from the command line and perform various maintenance tasks for your application.

< Rails Console for DB >
> rails dbconsole

< Removes autogenerated files created by generate >
> rails destroy ModelName

< Executes a method in your application outside the context of the Web >
> rails runner Order.test

<< 1. Active Record >>

< ActiveRecord's db attributes >
> run 'TableName.column_names' in 'rails console' to show all the columns of the given TableName
> run 'TableName.columns_hash['column_name']' to view detail info of the given column name

< Get raw value of attributes >
> run 'TableName.column_name_before_type_cast' 

< Mapping SQL Types with Ruby >
SQL Type		Ruby Class
int, integer		Fixnum
float, double		Float
decimal, numeric	BigDecimal
char, varchar, string	String
interval, date 		Date
datetime, time 		Time
clob, blob, text 	String
boolean 		See text

< Like Clause >
> User.where("name like ?", params[:name]+"%")

<< Concern >>
> If you find yourself repeating code, consider using concerns.

<< 2. Action Pack >>
> consists of three Ruby modules: ActionDispatch , ActionController , and ActionView

< ActionDispatch >
> routes requests to controllers

< ActionController >
> converts requests to responses

< ActionView >
> is used by ActionController to format those responses

< ActionDispatch >
  < Routes >
  > Adding language to routes
    scope '(:locale)' do
     resources :orders
    end

  > Making routes reusable
     concern :reviewable do
      resources :reviews
     end
     resources :products, concern: :reviewable
     resources :users, concern: :reviewable
  > Shallow Route Nesting
       resources :products, shallow: true do
        resources :reviews
       end
< View >
> Overriding the deault location of "views" from "app/views" to smth
> ActionController.prepend_view_path dir_path

< Render Method >
> render(action: 'fake_action_name')
> render(template: 'controller/name')
> render(file: 'dir/template')

< Overriding default location of layout >
> class StoreController < ApplicationController
>	layout "standard", except: [ :rss, :atom ]
>	# ...
> end

< Spacer_template >
> :spacer_template parameter lets you specify a template that will be rendered between each of the elements in the collection
><%= render(partial: "animal", collection: %w{ ant bee cat dog elk }, spacer_template: "spacer") %>

<< Migrations >>

< Run a specific version migration >
> rails db:migrate VERSION=20160330000009

< Running multiple old migrations back >
> rails db:migrate:redo STEP=3

< Custom Messages and Benchmarking in migration file >
>def up
  say_with_time "Updating prices..." do
   Person.all.each do |p|
    p.update_attribute :price, p.lookup_master_price
   end
  end
 end

<< Rake for automating tasks >>
< List rake tasks of db:setup >
> rake --trace --dry-run db:setup