Checking if a number is prime in Ruby

Go to irb :

 > require 'prime'
 => true
 > Prime.prime?(2)
 => true
 > Prime.prime?(3)
 => true
 > Prime.prime?(10)
 => false

Configuring Guard to Display output in Red Green Colors

Change the Guard file guard method to:

guard :rspec, cmd: 'rspec --color --format doc' do

... contents unchanged

end

From the root of the project run: guard

You will now see the colors in the terminal whenever the test is run.

Alternative to using take and drop methods in Array class

The take method takes elements from the beginning whereas the drop takes the elements from the end of the array. These methods require some mental mapping of the method names to what it does. I was thinking about reducing this gap. Here is the experiment in the IRB:

2.0.0 > a = [1,2,3,4]
 => [1, 2, 3, 4]
2.0.0 > a.first(2)
 => [1, 2]
2.0.0 > a
 => [1, 2, 3, 4]
2.0.0 > a.last(2)
 => [3, 4]
2.0.0 > a
 => [1, 2, 3, 4]

It just works! This is one of the reason why I love Ruby.

Using Bundler to install local gem in Rails project

gem 'mygem', :path => '/path/to/my/gem'

Things I love about Bundler

How to count number of files in a bucket in S3 recursively

1. git clone https://github.com/s3tools/s3cmd
2. cd s3cmd
3. s3cmd --configure
Enter the Amazon credentials.
4. ./s3cmd ls --recursive s3://your-bucket/another-bucket/foo

This will recursively find all the folders under foo and list all the files.

5. You can pipe it to wc to get the number of files like this :
     ./s3cmd ls --recursive s3://your-bucket/another-bucket/foo | wc -l

   

Loading rubyzip gem in irb

LoadError: cannot load such file -- rubyzip

Instead of : require 'rubyzip' use require 'zip'

Turn off Bonjour Notifications in Cyberduck

On Mac OS, run the following command in a terminal:

defaults write ch.sudo.cyberduck rendezvous.enable false

Reference:

Diable Bonjour in Cyberduck

Using MIME types outside of Rails 4

In a IRB session:

require 'action_dispatch/http/mime_type.rb'
 => true
> MIME::Types.type_for('a.pdf')

SimpleDelegator in Ruby

require 'delegate'

class User
  def born_on
    'July 21'
  end
end

class UserDecorator < SimpleDelegator
  def birth_year
    born_on
  end
end

decorated_user = UserDecorator.new(User.new)
p decorated_user.birth_year  #=> July 21

psych.rb in `parse': found a tab character that violate intendation while scanning a plain scalar at

You will not be able to go the rails console. Go to the root directory of the rails project and fire up an irb session:

1. require 'yaml'
2. YAML::ENGINE.yamler = 'psych'
3. YAML.load_file('config/your-config-file.yml')

Autocorrect yaml file syntax errors: s.gsub!(/\t/, ' ')

This will reproduce the problem. See the line number of row to find the syntax error. Fix it by changing the tab to space.

RVM is not a function, selecting rubies with 'rvm use ...' will not work.

To fix this in Ubuntu 12.04, go to : Profile --> Preferences, Title and Command tab and check the box for 'Run command as a login shell'

Installing RVM on Ubuntu 12.04

1. sudo apt-get install curl
2. \curl -L https://get.rvm.io | bash -s stable
3. source ~/.rvm/scripts/rvm

Do not run OS updates in parallel when installing RVM.



Reference:
Install Ruby on Rails on Ubuntu 12.04

how to setup Textmate 2 to run mate from command line

Go to preferences --> Terminal and click 'Install' to install shell support.

If you get the error 'To open a bundled gem, set $EDITOR or $BUNDLER_EDITOR'
Add the following line to ~/.bash_profile:

export BUNDLER_EDITOR=mate

Setup Textmate 2 to use RVM

1. $ which rvm-auto-ruby
2. Add the following to ~/.tm_properties

TM_RUBY="/path/to/rvm-auto-ruby/from/step1/"

3. Restart Textmate 2
4. Run : puts RUBY_VERSION as a ruby file.

Ruby on Rails - Enterprise Application Development Notes

Business Processes

In building small business apps, a developer is endeavoring to model or support a business process.

To realize the maximum potential for small business application development, the developer needs to take on the role of analyzing the business process.

To keep up a supply of new work, the developer needs to identify potential new projects and development opportunities.

The key skill to being able to identify opportunities for new apps is an understanding of how businesses work. Study business processes.

Take courses on business management and management accounts. Checkout SBIC library and other libraries. It helps you to identify the best opportunities to improve business processes.

To be successful, build successful business apps. A business application is successful when an application generates a profit. Demonstrate that you can increase their profits. How do small applications generate profit? There are three ways to generate more profit within a business.

1. Increase sales by either increasing the number of sales or increasing the revenue from each sale (or less easily, both)
2. Reduce what it costs you to sell.
3. Spend as little as you can on the parts of the business that generate the least profit and minimize any resources given over to loss making activities.

Business apps can address all of these profit opportunities. Most businesses try to increase profits by increasing sales. It is usually far easier to increase profits by reducing costs and minimizing the time spent on loss making activities. It is in these areas that most opportunities for small business apps arise.

Here is some areas where opportunities for small applications arise:

1. Automate Simple Repetitive Jobs

A simple way to reduce costs is to reduce the time it takes to carry out repetitive tasks. Ex: CFO was spending 4 hours running reports. I created an application which generated the report in 5 minutes. That single simple application has saved 100s of hours of work, thereby freeing up the CFO to do more revenue generating work.

2. Rapid and Detailed Reporting

Actively go out and identify the opportunities that can be found within any business. Develop the skills to identify the opportunities for new apps. To do that successfully and repeatedly, you must learn to identify business processes that can be simplified, made more effective and efficient via a small app.

Cucumber Features

http://wiki.github.com/dchelimsky/rspec/rails

Feature: CSR account management
 In order to manage dispute calls
 As a CSR
 I want to create an account to login to the system

 Scenario: Successful account creation
     Given a login with "csr@somedomain.com" and password "secret"
     And login is the same as email address
     When I provide my login and desired password
     Then I should receive an account activation email at "csr@somedomain.com"

 Scenario: Successful account activation
   Given a valid activation link "http://www.somedomain.com/activation-string-for-csr"
   When I follow the activation link
   Then my account should be activated
   And I should be able to login using the login credentials provided during registration
 
 Scenario: Successful login
   Given a valid user name "csr@somedomain.com" and password "secret"
   When I provide my login credentials
   Then I should be logged in to my account with CSR role
   And I should be able to add additional users with CSR role

 Scenario: Forgot password
   Given a valid user name "csr@somedomain.com"
   And I follow forgot password link
   When I provide my email that I used during account registration
   Then I should receive a link to reset my password
   And I should be redirected to password recovery instructions page

 Scenario: Reset Password
   Given a valid reset password link "csr@somedomain.com" for my account in the password reset email
   When I follow the reset password link
   Then I should be able to provide a new password and confirm password
   And I should be able to login with my new password
   And the system sends password reset confirmation link for security purpose

 Scenario: Change the login id for logging into the system  
     Given a valid login id "csr@somedomain.com"
     When I provide my new desired login id "csr@newdomain.com"
     Then I should be able to login using my new login id "csr@newdomain.com"

 Scenario: Add new CSR account
   Given a CSR is logged-in
   When I provide new account details with valid login "newbie@something.com", password "verysecret" and confirm password "verysecret"
   Then the system should send account activation email to the new csr's email address (login id)
 
 Scenario: Successful logout
   Given a valid user name "csr@somedomain.com" and password "secret"
   When I logout
   Then the system should log me out of the system
   And I should not be able to use the features available only to logged in users
 
 Scenario: Features only available to logged in users
   Given a user is logged in
   When I go to my dashboard
   Then I should be able to add new account, update my login id, search, forgot password and logout

 Scenario: Features not available to users who are not logged in
   Given a user is not logged in
   When they access the CSR application
   Then I should not be able to add new account, update login id, search and logout
   And I should be able to login and also use forgot password feature

 Scenario: Failed account creation
   Given a login with characters that is not in the whitelist
   When I provide my login (email address) and password
   Then I should not receive an account activation email
   And I should get an error message stating the password policy (8 to 40 characters in length with list of allowed characters)
   And the system prevents SQL inject attacks
 
 Scenario: Automatic login
   Given a valid login and the user enables remember me feature
   When I login
   Then I should be logged in automatically on subsequent visits to the site
 
 Scenario Outline: Failed Login
   Given the login id is "" and password is ""
   When I enter "" and ""
   Then the error message should be ""
 
 Scenarios: wrong login credentials
   | login         | password              | error                                         |
   | wrong email     | correct password | Email not found                            |
   | correct email | wrong password   | Wrong password                             |
   | wrong email     | wrong password   | Login and Password does not match  |
   

     

Including lib directory in the path in Rails 4

1. Add the line:

config.autoload_paths += %W(#{config.root}/lib)

to application.rb

2. Add your class to lib folder.

Rails 4 will now load the classes in the lib folder.

Syntax Highlighting for Rails

1. Add rouge and redcarpet gems to Gemfile.

gem 'rouge'

gem 'redcarpet'

2. Install rouge gem.

$ bundle

3. Create initializer in config/initializers/rouge.rb

require 'rouge/plugins/redcarpet'

class CustomHtml < Redcarpet::Render::HTML
  include Rouge::Plugins::Redcarpet # yep, that's it.
end

4.  Use the HTML class as a renderer in markdown method in app/helper/application_helper.rb:

def markdown(text)
  render_options = {
    filter_html:     true,
    hard_wrap:       true, 
    link_attributes: { rel: 'nofollow' }
  }
  renderer = CustomHtml.new(render_options)

  extensions = {
    autolink:           true,
    fenced_code_blocks: true,
    lax_spacing:        true,
    no_intra_emphasis:  true,
    strikethrough:      true,
    superscript:        true
  }
  Redcarpet::Markdown.new(renderer, extensions).render(text).html_safe
end

5.  For styling the output using Rouge built-in styles, create app/assets/stylesheets/rouge.css.erb with the following code:

<%= Rouge::Themes::ThankfulEyes.render(:scope => '.highlight') %>
or
<%= Rouge::Themes::Colorful.render(:scope => '.highlight') %>
or
<%= Rouge::Themes::Base16.render(:scope => '.highlight') %>

6. In your view app/views/articles/show.html.erb where you have markdown and code mixed, use the markdown helper:
 

  <%= markdown @article.content %>

References

1. Syntax Highlighting in Ruby on Rails

2. You can even use it with RedCarpet

Taking Passion to the Bank

Passion

Develop Web Applications that can become successful SaaS business.

Skill

Learn Full Stack Web Development using Rails.
Has a proven teaching system based on successful teaching methods.

Problem

Developers want to become Full Stack Rails Developer but are not able to learn quickly from existing resources.

Opportunity

Creates effective teaching material by making complicated concepts simple. Developers are able to master the material quickly.

Good businesses provide solutions to problems, in this case : 'How can I easily learn Web Application Development?'

Focusing on a specific geographical location

To focus my Google Adwords campaign for promoting lead generator ebook, I found all the unique IPs for the downleads by doing (rails 3.2 webapp):

ips = Download.select('DISTINCT ips')

list = ips.collect(&:ip)

Paste the ip list as a single column on the  Convert IP to Country website. Very interesting fact:

50% of the downloads is from USA. So it is better to follow the Google Ad support person's advice of targeting to one or two geographical locations.