README

This README would normally document whatever steps are necessary to get the application up and running.

Things you may want to cover:

Ruby version
System dependencies
Configuration
Database creation
Database initialization
How to run the test suite
Services (job queues, cache servers, search engines, etc.)
Deployment instructions
...

Test DB

It should echo nothing when everything goes well;

  rails db:schema:dump

Generate Controller

rails generate controller demo index

Default routes

Default routes will no longer be supported.

get ':controller(/:action(/:id))'

Root routes

root 'demo#index'

Simple routes

get 'demo/index'

Template

Vallina Ruby statements.

<%  %>

Erb file and it's template grammer.

<%= "bar #{foo}" %>

Double quotes are not supported in Ruby's template. (.erb file)

Conversation with controller.

// controller
@foo = "bar"

// erb
<%= "#{@foo}" %>

LinkTo

Erb template provides a built-in function--link_to for links.

<a href="/demo/index">index</a> // not recommend

<%= link_to(text, target) %>

<%= link_to("Back To Index", {controller: 'demo', action: "index"}) %>

if two pages are in the same controller, you needn't to pass the controller param;

Get url params

Link

// Url varies depends on your routes setting.
// Dynamic links to pass params to controllers
<%= link_to('hello', {:controller => 'demo', :action => 'index', :id => 55}) %>

There are two ways to get params from url.

// controller

@id = params['id']
@name = params[:name]

// view
<%= @id %>

Migration

Aim to ctrl database;
Written by Ruby;

rails generate migration DoTestDemo

Migration name must use camelcase.

Model

Generate a model.

rails g model User name:string email:string

Create mysql table;

rails db:migrate

Rollback;

rails db:rollback

Sandbox

Get into sandbox mode.

rails console --sandbox

Create users in sandbox mode.

ntnyq = User.new(name: "ntnyq", email: "me@ntnyq.com")

// Need validation pattern set.
ntnyq.valid?

ntnyq.save

// new and save in one step
goy = User.create(name: "goy", email: "goy@ntnyq.com")

View

// list all users
User.all

// show first user
User.first

Find One

User.find(id)

User.find_by(name: "goy")

Update

goy.name = "gay"
goy.save

goy.update_attribute(:name, "goy")

Delete

goy.delete

Validate

See more At Rails Validation

validates :name, { presence: true, length: {minimum: 5, maximum: 20} }

VALD_EMAIL_REGEXP = /\A[\w+\-.]+@[a-z\d\-]+(\.[a-z\d\-]+)*\.[a-z]+\z/i
validates :email, presence: true, length: { maximum: 20 },
          format: { width: VALD_EMAIL_REGEXP },
          uniqueness: { case_sensitive: false }

Mysql

Mysql suggest you using capitalize letters for it's key words.

DESCRIBE users;

Git

Create Branch

Create a branch and set it currently.

git checkout -b branch_name

Go Back To master

git checkout master

git checkout -

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