Programming in Ruby On Rails

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

First we need to install ruby Step 1)Install Ruby apt-get -y update apt-get -y install build-essential zlib1g-dev libssl-dev libreadline6-dev libyaml-dev cd /tmp wget http://cache.ruby-lang.org/pub/ruby/2.0/ruby-2.0.0-p247.tar.gz tar -xvzf ruby-2.0.0-p247.tar.gz cd ruby-2.0.0-p247/ ./configure --prefix=/usr/local make make install Step 2) Install Rails gem install rails 4.0.1 Step 3) Install passenger gem install passenger Step 4) Install Apache2 apt-get install apache2 Step 5) Install Mysql sudo apt-get install mysql-server mysql-client That's it we are done with the setup.

This is a powerful feature of rails to communicate between two models in two different application running in two different server. ActiveResource:Base is the main class for mapping RESTful resources as models in a Rails application. Active Resource objects represent your RESTful resources as manipulatable Ruby objects. To map resources to Ruby objects, Active Resource  only needs a class name that corresponds to the resource name (e.g., the class User maps to the resources Products, very similarly to Active Record) and a site value, which holds the URI of the resources. class User < ActiveResource::Base   self.site = "http://api.products.com:3000/" end In order to access products.com controller you need to send the json response like i am going to call the index action so we need to write :- def index @products = Product.all respond_to do |format| format.json { render :json => @products} end end Now the User class is mapped to RESTful resources located

Sending emails in a rails application is very easy and quite handy using action mailer. First we will go through the basic setup of action mailer then we will go in details how it works. Step 1   We can setup a mailer class using rails generator   rails generate mailer UserMailer Step 2   Then we can create any instance method inside it.     def welcome_email(user)       @user = user       @url  = 'http://example.com/login'       mail(to: @user.email, subject: 'Welcome')     end Step 3   We can call this method form model or controller or any kind of callbacks using    Like     UserMailer.welcome_email(@user).deliver Step 4   You can set up a view template for the welcome_email in side the views/mailer directory   Like   welcome_email.html.erb   and you can specify the layout format here and can also access the instance variables defined in the       welcome_email(user) method Step 5   Additionally we can set up the smtp configuration inside

1) tail cannot watch no space left on device.    Solutions   a)  echo 900000 | sudo tee /proc/sys/fs/inotify/max_user_watches      Or Place   b) "fs.inotify.max_user_watches=16384" in /etc/sysctl.conf 2)  How to remove all files and sub-directories in a directory WITHOUT deleting the directory in bash? Solutions rm -rfv dontDeleteMe/*

If you want to upload bulk file in rails application just follow the following steps 1) create a rails application     rails new bulk_upload 2) Add passenger in your gem file     gem 'passenger' Now try to start with your rails application with the command   passenger start by default it will run on port number 3000 Now if you try to upload bulk files lets just say more than 500 mb or 800 mb you will get an error in the time of uploading like [ error] 4840#0: *557 client intended to send too large body: 94672000 bytes, client: 127.0.0.1, server: _, request: "POST /XXX HTTP/1.1", host: "localhost:3000" so this not error of you application this is the error thrown by passenger and ngnix which is responsible to run passenger First uninstall using purge to remove even configuration files and records:   apt-get purge nginx nginx-common nginx-full Then reinstall it  apt-get install nginx If above doesn't work for you you can also