Author: Kallala

How to install Devise in Rails 3.x

Posted on by Kallala

ror41-150x150Devise is a flexible authentication solution for Rails based on Warden. Devise handles authentication across the entire stack. It has the following features:

  • Rack based
  • MVC based on Rails engines
  • Allows you to have multiple roles (or models/scopes) signed in at the same time
  • Modularity concept: use just what you really need

It is composed of 12 modules:

  • Database Authenticatable
  • Token Authenticatable
  • Omniauthable
  • Confirmable
  • Recoverable
  • Registerable
  • Rememberable
  • Trackable
  • Timeoutable
  • Validatable
  • Lockable

Steps to install the Devise

Step#1

Add the following gem in your Gemfile

gem 'devise'

Then run

bundle install

Step#2

To invoke the Devise in your application, run the devise generator

 rails g devise:install

The generator will install an initialize, which describes all devise’s configuration options.

Step#3

Create a model “User” using devise to handle authentication.

rails g devise User

This generator creates a few interesting things like a file, a migration and a devise_for in route.

Step#4

Run the migration

rake db:migrate

Step#5

Devise provides some helper methods to recognize a user after sign in and default route paths for “sign in”, “sign up” and “sign out”

We can modify our ‘app/views/layout/application.html.erb’ file to allow us to “sign out”, “sign in” and “sign up” by writing the following block

<div>
<% if user_signed_in? %>
Signed in as <%= current_user.email %>. Not you?
<%= link_to "Sign out", destroy_user_session_path,:method => :delete %>
<% else %>
<%= link_to "Sign up", new_user_registration_path %> or
<%= link_to "Sign in", new_user_session_path %>
<% end %>
</div>

Configuring views

Since Devise is an engine, all its views are packaged inside the devise gem.

Get all the view files for devise by running the following generate command

rails generate devise:views

You can also configure the message language, mailer from address and other things by editing the devise config files as located in following locations

devise.en.yml – config/locales
 
devise.rb – config/initializers

Now you are done to use the app with authentication!

How To Implement Event Calendar In Rails App

Posted on by Kallala

Event calendar is a way to show multiple, overlapping events across calendar days and rows. This is an interface to add events, edit events, & destroy event. In Rails there is a gem/plugin “event_calendar” to implement it just like Google calendar.

The following steps demonstrate the implementation of event_calendar in both Rails 2.3.x and Rails3.x environment.

Step#1 –

Installing the gem/plugin

  • In rails 2.3.x

Install the required plugin from below path

script/plugin install git://github.com/elevation/event_calendar.git

Generate the necessary static file and example

script/generate event_calendar
  • In rails 3.x

Install the required gems

gem 'event-calendar', :require => 'event_calendar'

Run “bundle install”

You can also use as a Plugin, to install plugin

rails plugin install git://github.com/elevation/event_calendar.git

Generate the necessary static file for the event calendar

rails generate event_calendar

Step#2

Include the necessary style sheet & java-script into your layout/view

<%= stylesheet_link_tag "dialog","fullcalendar","jquery-ui","style" %>
<%= javascript_include_tag "jrails1/fullcalendar.js","jrails1/jquery-
ui.js","jrails1/gcal.js","jrails1/jrails.js","jrails1/jquery.validate.js"%>

Step#3

Create a migration file to add necessary columns as follows

class CreateEvents < ActiveRecord::Migration
def self.up
create_table :events do |t|
t.string :name
t.datetime :start_at
t.datetime :end_at
t.timestamps
end
end
def self.down
drop_table :events
end
end

Step#4

Add the necessary paths to the “config/routes” file

  • In Rails 2.3.x
map.calendar '/calendar/:year/:month', :controller => 'calendar', :action => 'index',
 
:requirements => {:year => /d{4}/, :month => /d{1,2}/}, :year => nil, :month => nil
  • In Rails3.x
match '/calendar(/:year(/:month))' => 'calendar#index', :as => :calendar, :constraints => {:year => /d{4}/, :month => /d{1,2}/}

Step#5

Change the Event model to add the calendar as follows

class Event < ActiveRecord::Base
has_event_calendar
end

Step#6

Modify the Calendar controller as follows

class CalendarController < ApplicationController
def index
@month = (params[:month] || Time.zone.now.month).to_i
@year = (params[:year] || Time.zone.now.year).to_i
@shown_month = Date.civil(@year, @month)
@event_strips = Event.event_strips_for_month(@shown_month)
end
end

Step#7

You can also override the events method in helpers/calendar_helper.rb

module CalendarHelper
def month_link(month_date)
link_to(I18n.localize(month_date, :format => "%B"), {:month => month_date.month, :year => month_date.year})
end
# custom options for this calendar
def event_calendar_options
{
:year => @year,
:month => @month,
:event_strips => @event_strips,
:month_name_text => I18n.localize(@shown_month, :format => "%B %Y"),
:previous_month_text => "<< " + month_link(@shown_month.prev_month),
:next_month_text => month_link(@shown_month.next_month) + " >>"
}
end
def event_calendar
calendar event_calendar_options do |args|
event = args[:event]
%(<a href="/events/#{event.id}" title="#{h(event.name)}">#{h(event.name)}</a>)
end
end
end

Step#8

Add the following code to display the calendar in the view file

<%= event_calendar %>

See Also: Security Checks you must do before Rails App release

I hope it helps you. Planning anything in Ruby on Rails? Get in touch with Andolasoft experts. Feel free to give your valuable feedback.

How to shorten URL using “bitly.com” in Rails 3.x

Posted on by Kallala

rorURL shortening is a technique on the World Wide Web (WWW) in which a Uniform Resource Locator (URL) may be made substantially shorter in length and still direct to the required page.

This is achieved by using an HTTP Redirect on a domain name that is short, which links to the web page that has a long URL. This is especially convenient for messaging technologies such as Twitter and Identical which severely limit the number of characters that may be used in a message.

Many web developers pass descriptive attributes in the URL to represent data hierarchies, command structures, transaction paths or session information. This can result in URLs that are hundreds of characters long and that contain complex character patterns. Such URLs are difficult to memorize and manually reproduce. As a result, long URLs must be copied-and-pasted for reliability. Thus, short URLs are more convenient for websites.

Step# 1

  • To begin with, create an account at bit.ly “
  • Get your API key by the following URL

“http://bit.ly/account/your_api_key/”

Step# 2

  • In rails 3.x

Write the following gems in your gemfile

gem 'bitly'
  • Run “bundle install”

Step# 3

Add the following code in your controller

require 'bitly'

Step# 4

Bitly recently released their version 3 API. From this 0.5.0 release, the gem will continue to work the same but also provide a V3 module, using the version 3 API. The standard module will become deprecated, as Bitly do not plan to keep the version 2 API around f orever.

To move to using the version 3 API, call in you top of the controller:

Bitly.use_api_version_3

Step# 5

To shorten a URL

bitly = Bitly.new('your-bitly-user-id','your-bitly-api-key') page_url = bitly.shorten('your-url') shorten_url = page_url.short_url

It will generate the bitly URL similar to “http://bit.ly/7BWXcQ”

Polymorphic Associations in Rails3

Posted on by Kallala

ror31In polymorphic associations, a model can belong to more than one model, on a single association.

Here is an example where a model is associated with two other models in Rails3. For example we have Events and Article model which have comments. So the “Comment” model is common between the “Event” and “Article” model. Here are the steps to implement the polymorphic association between these three models.

Step#1
Let’s create a resource “Comment” by rails generator.

rails g scaffold Comment content:text

Step#2

Add associations in the models as below

Comment model:

class Comment < ActiveRecord::Base
attr_accessible :commentable_id, :commentable_type, :content
belongs_to :commentable, :polymorphic => true  #Now, it is acted as polymorphic
end

Event model:

class Event < ActiveRecord::Base
attr_accessible :name
has_many :comments, :as => :commentable
end

Article model:

class Article < ActiveRecord::Base
attr_accessible :name
has_many :comments, :as => :commentable
end

Step#3

Add the following attributes in the migration files of the comment model

Look for newly created file under “db/migrate” folder

class CreateComments < ActiveRecord::Migration
def change
create_table :comments do |t|
t.text :content
t.references :commentable, :polymorphic => true
t.timestamps
end
end
end

Then execute rake db: migrate in the command line

Step#4

Add nested resources inside the “config/routes.rb” file

resources :events  do
resources :comments
end
resources :articles do
resources :comments
end

Step#5

Add link to add new comments in view page of article and events as follows

In “/app/views/events/show.html.erb”

<%= link_to 'New comment', new_event_comment_path(@event)  %>

In /app/views/articles/show.html.erb

<%= link_to 'New comment', new_article_comment_path(@article)  %>

Step#6

Changing the form_for tag in new comment page

In “/app/views/comments/_form.html.erb”

Before

<%= form_for (@comment) do |f| %>

After

<%= form_for [@commentable, @comment] do |f| %>

Add following codes in both “Articles” & “Events” controllers to get the comments individually

In “/app/controllers/events_controller.rb”

def show
@event = Event.find(params[:id])
@comments= @event.comments #added to view all the comments for the selected event
respond_to do |format|
format.html # show.html.erb
format.json { render json: @event }
end
end

In “/app/controllers/articles_controller.rb”

def show
@article = Article.find(params[:id])
@comments= @article.comments #added to view all the comments for the selected article
respond_to do |format|
format.html # show.html.erb
format.json { render json: @article }
end
end

Step#8

Add the following codes to “Comments” controller to creating a comment

In “/app/controllers/comments_controller.rb”

class CommentsController < ApplicationController
def new
@commentable = find_commentable
@comment = Comment.new
end
def create
@commentable = find_commentable
@comment = @commentable.comments.build(params[:comment])
if @comment.save
flash[:notice] = "Successfully created comment."
redirect_to :id => nil
else
render :action => 'new'
end
end
 
private
 
def find_commentable
params.each do |name, value|
if name =~ /(.+)_id$/
return $1.classify.constantize.find(value)
end
end
nil
end
end

Now the comment model will work as a polymorphic association between article and event model.

Facebook Integration in Rails3 using ‘omniauth’ gem

Posted on by Kallala

feature11. Create a Facebook Application by using your ‘Facebook Developer account’
2. Get the ‘App ID’ and ‘App Secret’ of your created application

Add following gems to your Gemfile

  • gem ‘omniauth’
  • gem ‘omniauth-facebook’

Run ‘bundle install’

Create a middleware file named ‘omniauth.rb’ in ‘config/initializers’ path

Rails.application.config.middleware.use OmniAuth::Builder do
provider :facebook, ENV['FACEBOOK_KEY'], ENV['FACEBOOK_SECRET'],
{:scope ≥ 'email, read_stream, read_friendlists, friends_likes, friends_status, offline_access, publish_stream'}
end

This will hold the facebook_app_key and facebook_secret_key with permissions

Set your custom callback url in routes

match '/auth/:provider/callback', :to ≥ 'sessions#create' match '/auth/failure', :to ≥ 'sessions#failure'

Write the following codes in the Sessions Controller

def create
auth_hash = request.env['omniauth.auth'] # Got The precise information from facebook
if  !auth_hash.nil?
@user = User.find_or_create_from_auth_hash(auth_hash)
self.current_user = @user
redirect_to '/'
end
end
def failure
flash[:notice] = "Sorry, but you didn't allow access to our app!"
redirect_to '/'
end

Write the following code in your view page. You can use a custom image for the Facebook like ‘facebook.png’.

<%=link_to image_tag('/images/facebook.png'),
"/auth/facebook" %>

How to use Nested Attributes in Rails 3 Forms

Posted on by Kallala

For example, say we want to add multiple addresses(attributes) having many fields inside a create/edit employee form

Step# 1

  •         Create a model named Employee
  •         Create another model named Address
  •         Add the following relationship in Employee model
class Employee < ActiveRecord::Base
has_many :addresses, :dependent => :destroy
accepts_nested_attributes_for :addresses, :reject_if => lambda { |a| a[:city].blank? }
end
  •    Nested attribute form rejects if the city field of the address is blank

Step# 2

  •        In Employees controller add the following in the “new” action
def new
@employee = Employee.new
@employee.addresses << Address.new
end

Step# 3

  •         In the view file add the following inside the form attribute
<%= form_for @employee, :html => { :multipart => true, :id => 'new-employee' } do |f|
<%= f.label :name, 'Name' %>
<%= f.text_field :name %>
 
<% end %>