td mxc rubyrails shin

8/14/2019 TD MXC RubyRails Shin

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Rapid WebRapid Web

ApplicationApplicationDevelopment usingDevelopment usingRuby on RailsRuby on Rails

Sang ShinSang ShinSun Microsystems, Inc.Sun Microsystems, Inc.javapassion.comjavapassion.com

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Topics

What is and Why Ruby on Rails (Rails)? Rails Basics

Step by step for building Hello World Rails application

ActiveRecord ActionController

ActionView

Deployment


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What is and WhyWhat is and WhyRuby on Rails (RoR)?Ruby on Rails (RoR)?


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What Is Ruby on Rails?

A full-stack MVC web development framework

Written in Ruby

First released in 2004 byDavid Heinemeier Hansson

Gaining popularity


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Ruby on Rails Principles

Convention over configuration> Why punish the common cases?

> Encourages standard practices

> Everything simpler and smaller Dont Repeat Yourself (DRY)

> Repetitive code is harmful to adaptability

Agile development environment> No recompile, deploy, restart cycles

> Simple tools to generate code quickly

> Testing built into the framework


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Rails BasicsRails Basics


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Ruby on Rails MVC

source: http://www.ilug-cal.org


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Step By Step ProcessStep By Step Processof Building Hello Worldof Building Hello World

Rails ApplicationRails Application


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Steps to Follow

1.Create Ruby on Rails project

> IDE generate necessary directories and files

2.Create and populate database tables3.Create Models (through Rails Generator)

> Migrate database

4.Create Controllers (through Rails Generator)5.Create Views

6.Set URL Routing

> Map URL to controller and action


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Demo:Demo:Building Hello WorldBuilding Hello World

Rails Application Step by Step.Rails Application Step by Step.

http://www.javapassion.com/handsonlabs/rails_basics/#Exercise_1http://www.javapassion.com/handsonlabs/rails_basics/#Exercise_1


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Key Learning Points

How to create a Rails project

> Rails application directory structure

> Concept of environments - development, test, and

production

How to create a database using Rake

How to create and populate tables using Migration

How to create a model using Generator

How to use Rails console


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Key Learning Points

How to create a controller using Generator

> How to add actions to a controller

How to create a related view

> How a controller and a view are related

> How to create instance variables in an action and theyare used in a view

How to set up a routing

How to trouble-shoot a problem


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Demo:Demo:How to create an input form.How to create an input form.

http://www.javapassion.com/handsonlabs/rails_basics/#Exercise_4http://www.javapassion.com/handsonlabs/rails_basics/#Exercise_4


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Key Learning Points

How to use form_tag and text_fieldhelpers tocreate an input form

How input form fields are accessed in an action

method throughparams


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ScaffoldingScaffolding


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What is Scaffolding?

Scaffolding is a way to quickly create a CRUDapplication

> Rails framework generates a set of actions for listing,

showing, creating, updating, and destroying objects ofthe class

> These standardized actions come with both controllerlogic and default templates that through introspectionalready know which fields to display and which inputtypes to use

Supports RESTful view of the a Model


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Demo:Demo:

Creating a Rails ApplicationCreating a Rails Applicationusing Scaffoldingusing Scaffolding

http://www.javapassion.com/handsonlabs/rails_scaffold/#Exercise_1http://www.javapassion.com/handsonlabs/rails_scaffold/#Exercise_1


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Key Learning Points

How to perform scaffolding using Generator

What action methods are created throughscaffolding

What templates are created through scaffolding


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ActiveRecordActiveRecordBasicsBasics


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ActiveRecord Basics

Model (from MVC)

Object Relation Mapping library

> A table maps to a Ruby class (Model)

> A row maps to a Ruby object

> Columns map to attributes

Database agnostic

Your model class extendsActiveRecord::Base


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ActiveRecord Class

Your model class extendsActiveRecord::Base

class User [ "user_name = ? ANDpassword = ?", user_name, password ])

end

end


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Naming Conventions

Table names are plural and class names aresingular

> posts (table), Post(class)

> students (table), Student(class)

> people (table), Person (class)

Tables contain a column named id


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Find: Examples

find by id

Person.find(1) # returns the object for ID = 1

Person.find(1, 2, 6) # returns an array for objects with IDs in (1, 2, 6)

find firstPerson.find(:first) # returns the first object fetched by SELECT * FROM peo

Person.find(:first, :conditions => [ "user_name = ?", user_name])

Person.find(:first, :order => "created_on DESC", :offset => 5)


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Dynamic attribute-based finders

Dynamic attribute-based finders are a cleaner wayof getting (and/or creating) objects by simplequeries without turning to SQL

They work by appending the name of an attribute tofind_by_orfind_all_by_, so you get finders like

> Person.find_by_user_name(user_name)

> Person.find(:first, :conditions => ["user_name = ?",user_name])

> Person.find_all_by_last_name(last_name)> Person.find(:all, :conditions => ["last_name = ?", last_name])

>Payment.find_by_transaction_id


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ActiveRecordActiveRecordMigrationMigration


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ActiveRecord Migration

Provides version control of database schema

> Adding a new field to a table

> Removing a field from an existing table

> Changing the name of the column

> Creating a new table

Each change in schema is represented in pure

Ruby code


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Example: Migration

Add a boolean flag to the accounts table and remove itagain, if youre backing out of the migration.

class AddSsl < ActiveRecord::Migration def self.up

add_column :accounts, :ssl_enabled, :boolean, :default => 1end

def self.downremove_column :accounts, :ssl_enabled

end

end


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Demo:Demo:How to add a field to a tableHow to add a field to a table

using Migrationusing Migration

http://www.javapassion.com/handsonlabs/rails_scaffold/#Exercise_2http://www.javapassion.com/handsonlabs/rails_scaffold/#Exercise_2


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Key Learning Points

How to add a new field to a table using Migration

How to create a migration file using Generator

How to see a log file


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ActiveRecordActiveRecordValidationValidation


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ActiveRecord::Validations

Validation methods

class User < ActiveRecord::Base

validates_presence_of :username, :level

validates_uniqueness_of :username

validates_oak_id :username

validates_length_of :username, :maximum => 3, :allow_nil

validates_numericality_of :value, :on => :create

end


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Validation


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Demo:Demo:ValidationValidation

http://www.javapassion.com/handsonlabs/rails_scaffold/#2.4http://www.javapassion.com/handsonlabs/rails_scaffold/#2.4


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Associations

Associations are a set of macro-like class methodsfor tying objects together through foreign keys.

They express relationships like "Project has one

Project Manager" or "Project belongs to a Portfolio".

Each macro adds a number of methods to the classwhich are specialized according to the collection or

association symbol and the options hash. Cardinality

> One-to-one, One-to-many, Many-to-many


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One-to-many

Use has_manyin the base, and belongs_to in theassociated model

class Manager < ActiveRecord::Base

has_many:employees

end

class Employee < ActiveRecord::Base belongs_to :manager # foreign key - manager_id

end


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Demo:Demo:

AssociationAssociation

http://www.javapassion.com/handsonlabs/rails_activerecord/http://www.javapassion.com/handsonlabs/rails_activerecord/


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ActionControllerActionControllerBasicsBasics


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ActionController

Controller is made up of one or more actions that areexecuted on request and then either render a template orredirect to another action

An action is defined as a public method on the controller,which will automatically be made accessible to the web-server through Rails Routes

Actions, by default, render a template in the app/views

directory corresponding to the name of the controller andaction after executing code in the action.


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ActionController

For example, the indexaction of the GuestBookControllerwouldrender the template app/views/guestbook/index.erb by defaultafter populating the @entries instance variable.

class GuestBookController < ActionController::Base

def index@entries = Entry.find(:all)

end

def signEntry.create(params[:entry])redirect_to :action => "index"

end

end


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DeploymentDeployment


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Web Servers

By default, Rails will try to use Mongrel and lighttpdif they are installed, otherwise Rails will useWEBrick, the webserver that ships with Ruby.

Java Server integration> Goldspike

> GlassFish V3


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Goldspike

Rails Plugin

Packages Rails application as WAR

WAR contains a servlet that translates data from theservlet request to the Rails dispatcher

Works for any servlet container

rake war:standalone:create


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Demo:Demo:Deployment throughDeployment through

GoldspikeGoldspike

http://www.javapassion.com/handsonlabs/rails_deploy/#Exercise_1http://www.javapassion.com/handsonlabs/rails_deploy/#Exercise_1


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JRuby on RailsJRuby on Rails


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Why JRuby on Rails

over Ruby on Rails? Java technology production environments pervasive

> Easier to switch framework vs. whole architecture

> Lower barrier to entry

Integration with Java technology libraries,legacy services

No need to leave Java technology servers, libraries,reliability

Deployment to Java application servers


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JRuby on Rails: Java EE Platform

Pool database connections

Access any Java Naming and Directory Interface

(J.N.D.I.) API resource

Access any Java EE platform TLA:

> Java Persistence API (JPA)

> Java Management Extensions (JMX)

> Enterprise JavaBeans (EJB)

> Java Message Service (JMS) API

> SOAP/WSDL/SOA


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Rapid WebRapid Web

ApplicationApplicationDevelopment usingDevelopment usingRuby on RailsRuby on Rails

Sang ShinSang ShinSun Microsystems, Inc.Sun Microsystems, Inc.javapassion.comjavapassion.com

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