Programming in Ruby On Rails

Imagine a scenario where you have to create a report and send it to multiple clients, so lets just say you have a report model and you have client and you have report client model. lets first check all the association and model structure. #report model class Report < ActiveRecord::Base   has_many :report_clients   has_many :clients, through: :report_clients end #report_client class ReportClient < ActiveRecord::Base   belongs_to :report   belongs_to :client end #clients class Client < ActiveRecord::Base   has_many :report_clients   has_many :reports, through: :report_clients end No lets say you want to create a report for 30 clients. You can do that by adding nested attributes in rails. so our report model will became  class Report < ActiveRecord::Base   has_many :report_clients   has_many :clients, through: :report_clients   accepts_nested_attributes_for :report_clients, :reject_if => proc { |attributes| att

Imagine a scenario where you have to create a report and send it to multiple clients, so lets just say you have a report model and you have client and you have report client model. lets first check all the association and model structure. #report model class Report < ActiveRecord::Base   has_many :report_clients   has_many :clients, through: :report_clients end #report_client class ReportClient < ActiveRecord::Base   belongs_to :report   belongs_to :client end #clients class Client < ActiveRecord::Base   has_many :report_clients   has_many :reports, through: :report_clients end No lets say you want to create a report for 30 clients. You can do that by adding nested attributes in rails. so our report model will became  class Report < ActiveRecord::Base   has_many :report_clients   has_many :clients, through: :report_clients   accepts_nested_attributes_for :report_clients, :reject_if => proc { |attributes| att

Every one might have face the problem that Postgres id not running after OSX is crashed. Every time you try to start the Postgres server it will say : - another server might be running; trying to start server anyway You can follow the below steps to get rid of the problem. Step 1: Open your terminal and run   pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start   It will Say   pg_ctl: another server might be running; trying to start server anyway Step 2:  Check the log $ tail -f /usr/local/var/postgres/server.log It will print something like this FATAL:  lock file "postmaster.pid" already exists HINT:  Is another postmaster (PID 326) running in data directory "/usr/local/var/postgres"? FATAL:  lock file "postmaster.pid" already exists HINT:  Is another postmaster (PID 326) running in data directory "/usr/local/var/postgres"? Step 3: Delete the PID file. $ rm /usr/local/var/postgres/postmaster.pid S

Please follow the below steps to i nstall RVM RUBY RAILS and Postgres in MAC yosemite. Step 1. Install Homebrew Homebrew is a package manager for the Mac. Installing Homebrew by issuing the following command: ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install) " To make sure Homebrew is installed correctly run: brew doctor Step 2: Install GPG Package. Download and install the GPG package from the link https://gpgtools.org Step 3: Install RVM gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 and \curl -sSL https://get.rvm.io | bash -s stable Reload your bash_profile, so it can initialize RVM. ~/.bashrc Run RVM requirements to install basic required packages with Homebrew. Accept the license agreement and install Xcode Tools. After installing the tools continue the rvm requirements installation. rvm requirements Step 4. Install Requir

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.