Restful Rails

8/10/2019 Restful Rails

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by Olivier AnsaldiRESTful Rails
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REST

crashcourse
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client-server

stateless

cache

uniform interface

layered system

code-on-demand

REST constraints


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resource

resource identifier

representation

representation metadata

resource metadata

control data

REST data elements


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REST in Rails
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manipulated via HTTP methods

URL addressable entity

represented in different formats

Rails resource


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Rails resource

mani ulationsoperation SQL REST

create insert POST

read select GET

update update PUT

delete delete DELETE


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Rails resource URLs

Traditional Rails RESTful Rails

POST /post/create POST /post

GET /post/show/1 GET /post/1

POST /post/update/1 PUT /post/1

POST /post/destroy/1 DELETE /post/1


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Rails resource

re resentations

one controller

multiple representations

respond_to
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./script/generate scaffold_resource \ post \

title:string \

content:text \

created_at:datetime

Creating a resource


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Creating a resource

creates

model, views, controller, helper

fixtures, unit tests, functional tests,

migration (fully functional!)

modifies

config/routes.rb


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Model

app/models/post.rb

class Post < ActiveRecord::Base

end

nothing new!
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Views

app/views/posts/show.rhtml

Title:

Content:

Created at:

|

new syntax for link_toURLs!


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Views: routes

config/routes.rbActionController::Routing::Routes.draw do |map|

map.resources :posts

end

defines path methods and URL methods


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Views: routes

Action HTTP re uest Path methodindex GET /posts projects_path

show GET /posts/1 project_path(1)

new GET /posts/new new_project_path

edit GET /posts/1;edit edit_project_path(1)

create POST /posts projects_path

u date PUT /posts/1 project_path(1)

delete DELETE /posts/1 project_path(1)


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Views: routes

new

form_for(:post, :url => post_path)...

edit

form_for(:post, :url => post_path(@post), \

:html => {:method => :put})...

destroy

link_to Destroy, post_path(post), :method => :delete
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Controller

app/controllers/posts_controller.rb

def destroy

@post = Post.find(params[:id]) @post.destroy

respond_to do |format|

format.html { redirect_to posts_url }

format.xml { head :ok }

end

end

uses respond_toand post_url


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Controller: routes

Traditional Rails

redirect_to :controller => posts, \

:action => show, :id => @post.id

RESTful Rails

redirect_to post_url(@post)

Each path method has equivalent URL method

Remember: use URL methods for redirect_to


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Controller: respond_to

multiple representations of the resource

respond_touses

accept HTTP-Header of the request

format appended to the request URL

register new formats in config/environment.rbto extend responds_to

Mime::Type.register image/png, :png


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Migration

db/migrate/001_create_posts.rb

class CreatePosts < ActiveRecord::Migration

def self.up

create_table :posts do |t|

t.column :title, :string

t.column :content, :text

t.column :created_at, :datetime

end

end

def self.down

drop_table :posts

end

end
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Nested resources

strongly coupled resources

expressed in the URLs

creating a nested resource

./script/generate scaffold_resource comment \

post_id:integer created_at:datetime \ author:string content:text


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Nested resources:

modelsmodels must be edited to express relationship

app/models/post.rb

class Post < ActiveRecord::Base

has_many :comments

end

app/models/comment.rb

class Comment < ActiveRecord::Base

belongs_to :post

end


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Nested resources:

routesroutes must be edited to reflect relationship

config/routes.rbmap.resources :comments

becomes

map.resources :posts do |posts| posts.resources :comments

end


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Nested resources:

routesPath method Path

comments_path(1) /posts/1/comments

comment_path(1, 2) /posts/1/comments/2

new_comment_path(1) /posts/1/comments/new

edit_comment_path(1) /posts/1/comments/2;edit


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Nested resources:

controller

nested resources controllers must be adapteddef index

post = Post.find(params[:post_id])

@comments = post.comments.find(:all)

...

end


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Thinking in REST terms

Resources represent

objects

relationships

events

states
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REST benefits

clean URLS

multiple representations

less code

CRUD oriented controllers

clear application design

scalability


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Documents

Restful Rails