Programming in Ruby On Rails

In Rails we create simple form and also sometimes we need nested form. In Rails we can easily do that using  gem “nested_form”. let's create a project using “nested_form”. Before that I would like to ask you to have a look on nested_attribute_documentation(http://api.rubyonrails.org/classes/ActiveRecord/NestedAttributes/ClassMethods.html#method-i-accepts_nested_attributes_for). 1) Create a new Rails 4 Project.     rails new nested_app 2) Include the gem in your gem file.   gem "nested_form" 3) run bundle install  bundle install 4) Generate the necessary javascript file.   rails g nested_form:install 5) Include the javascript file in the asset pipeline. in the application.js add the below line.   //= require jquery_nested_form 6) Let say we have a Exam model and one Exam can have multiple Questions.So lets create the Exam model. class Exam < ActiveRecord::Base   has_many :questions, dependent: :destroy   accepts_nested_attributes_for :questions,

Postgres is a great open source database management system. It's pretty easy to use postgres with Ruby on Rails. Step 1: Install postgress in your system. If you already have postgres installed in your system then skip it else follow the  link . Step 2: Create new project rails new pg_demo You can also create using rails new pg_demo --database=postgresql Step 3: include the pg gem in your gem file gem 'pg' Step 4: run bundle command bundle Step 5: It will give you some error like An error occurred while installing pg (0.17.1), and Bundler cannot continue. Make sure that `gem install pg -v '0.17.1'` succeeds before bundling. So let's try to install the  pg gem first gem install pg It will again throw an error  :( Building native extensions.  This could take a while... ERROR:  Error installing pg: ERROR: Failed to build gem native extension.     /home/sabyasachi/.rvm/rubies/ruby-2.1.0/bin/ruby extconf.rb checking for pg_config... y

Step 1: Before postgres install, we should quick perform a quick update. apt-get update Step 2: Now install Postgres using the command line.   sudo apt-get install postgresql postgresql-contrib This will install the latest version available in your Ubuntu. Step 3: Install the client   sudo apt-get install postgresql-client Step 4:  For a handy GUI for PostgreSQL install pgAdmin III.  sudo apt-get install pgadmin3 Step 5:  We need to change the PostgreSQL postgres user password; sudo -u postgres psql postgres Set a password for the "postgres" database role using the command: \password postgres Step 6: Exit from Postgres   \q That's it we are done with the installation.  

Neo4j is a graph database, using neo4j gem( https://github.com/neo4jrb/neo4 j) we can easily use neo4j database in our ruby on rails application ( http://programminginrubyonrails.blogspot.in/2014/12/neo-4j-with-rails.html ). Till now neo4j gem does not support rake db tasks. You can check all the supported task by typing rake -T in your console. Now we can create our own custom rake task to seed some  data in neo4j . Step 1: Create a file under lib/tasks name it seed.rake Step 2: Put the below code in seed.rake. namespace :db do   desc 'Load the seed data from db/seeds.rb'   task :seed => :environment do     seed_file = File.join(Rails.root, 'db', 'seeds.rb')     load(seed_file) if File.exist?(seed_file)   end end That's it. now you can run rake db:seed from your terminal.. Simple :) 

How to setup new 4j database with Rails 4. Step 1: Install Neo4j Database in ubuntu.   login as Admin  sudo -i  wget -O - http://debian.neo4j.org/neotechnology.gpg.key | apt-key add -  Add Neo4J to the Apt sources list:   echo 'deb http://debian.neo4j.org/repo stable/' > /etc/apt/sources.list.d/neo4j.list  Update the package manager:  exit as admin  apt-get update  Install Neo4J:  apt-get install neo4j  sudo /etc/init.d/neo4j-service restart Step 2: Create a new rails project.  Rails new neo4j Step 3:  Add neo4j Gem in your gem file   gem 'neo4j', github: 'andreasronge/neo4j' Step 4: Go to application.rb require File.expand_path('../boot', __FILE__) require "rails" %w(   neo4j   action_controller   action_mailer   sprockets ).each do |framework|   begin     require "#{framework}/railtie"   rescue LoadError   end end # Require the gems listed in Gemfile, including any gems # you've

We can create a RESTful API using Grape and RABL in Rails4. Step 1: Add this GEMS in your Gem file, And do Bundle install.  gem 'grape'  gem 'rabl-rails'  gem 'grape-rabl'  gem 'rack-cors', :require => 'rack/cors' Step 2: Create a file under lib directory called api.rb, and create a folder inside the view named as api. # lib/api/v1/root.rb class API < Grape::API end Step 3: Add this line to your application.rb file    config.paths.add "app/api", glob: "**/*.rb"     config.autoload_paths += %W(#{config.root}/lib #{config.root}/app/api/*)     config.middleware.use Rack::Cors do       allow do         origins '*'         # location of your API         resource '/*', :headers => :any, :methods => [:get, :post, :options, :put, :delete]       end     end     config.middleware.use(Rack::Config) do |env|       env['api.tilt.root'] = Rails.root.join "app", "

How to set up jruby with apache and passenger in amazone ec2. Step 1: First install jruby using please check the current version in the   link . And make sure you are installing the bin version of it wget 'http://jruby.org.s3.amazonaws.com/downloads/1.7.4/jruby-bin-1.7.4.tar.gz' Step 2: extract the tar file using tar zxvf jruby-bin-1.7.4.tar.gz Step 3: We need to set come environment variable so that it will be accessible from every other place. export JRUBY_HOME=/home/home_directory_name/jruby-1.7.4 export PATH=$JRUBY_HOME/bin:$PATH And Open the .bashrc file and put the path in their sudo nano ~/.bashrc PATH=$PATH:/home/ubuntu/jruby-1.7.4/bin Step 4: Now to check if jruby is properly installed or not put jruby-v If your system does not have java installed then it will show an error like /home/ubuntu/jruby-1.7.4/bin/jruby: line 395: exec: java: not found Don't worry we will install java to fix this. sudo apt-get install openjdk-7-jdk apt-cache