Category: Ruby

Rails gem therubyracer installation error: extconf.rb:10:in `’: Error compiling V8 (RuntimeError)

It is because of you have already the old version of therubyracer is in your project. And that version depends on a libv8 gem, thats why it is getting error so, uninstall the libv8 gem and install the therubyracer again

$ gem uninstall libv8
$ gem install therubyracer

Importing contacts from your email using Rails ‘contacts’ gem

Using ‘contacts’ gem you can import all your contact emails.

Step 1:

In Your Gemfile add,

## For Importing Email Contacts
gem "contacts", :git => "git://github.com/abhilashak/contacts.git"
gem "gdata", :git => "git://github.com/abhilashak/gdata-1.git"

For importing from gmail, we need the gem ‘gdata’.

Do bundle install

you are done.

Step 2:

In your views/import_profile_contact/new.html.erb file,

<%=  text_field_tag "profile_contact[email]", "" %>

<%=  password_field_tag "profile_contact[password]", "" %>

Put one more hidden field tag to know that from which email the user need to import

<%= hidden_field_tag :contact_from, @contact_from %>

the values of @contact_from may be gmail, yahoo mail, hot mail. According to which option user clicks pass the corresponding string.

Step 3:

In your controller get the email and password params

@contact_from = params[:contact_from]

email = params[:profile_contact][:email]
password = params[:profile_contact][:password]

if @contact_from && email && password
  if @contact_from == "gmail"
    @imported_contacts = Contacts.new(:gmail, email, password).contacts
  elsif @contact_from == "yahoo_mail"
    @imported_contacts = Contacts.new(:yahoo, email, password).contacts
  elsif @contact_from == "hotmail"
    @imported_contacts = Contacts.new(:hotmail, email, password).contacts
  end
end

You will get all contacts in an array….

Install Rails 3.1.3 and set up in Linux

Install RVM

If you are not already installed RVM install from here:
https://rvm.beginrescueend.com/rvm/install/

If you already have rvm installed, update it to the latest version.

$ rvm get latest
$ rvm reload
$ rvm -v

Create a Rails 3.1.3 Gemset

Create a default Rails 3.1.3 gemset. It’s advisable to create a new gemset for each application you build. But to get started, create just one new Rails 3.1.3 gemset as your default.

$ rvm ruby-1.9.2-p290@rails313 --create --default

To see a list of the gemsets you have installed:

$ rvm gemset list

And see a list of the gems included with the standard Ruby installation:

$ gem list

$ rvm list gemsets

rvm gemsets

ruby-1.9.2-p290 [ i386 ]
ruby-1.9.2-p290@global [ i386 ]
=> ruby-1.9.2-p290@rails313 [ i386 ]

Make sure you are using the newest version of Rake before you install Rails 3.1.3.

$ gem update rake
$ rake --version

Install Rails

$ gem install rails -v "3.1.3"

DETAILS:

RVM Version

rvm 1.10.1 by Wayne E. Seguin <wayneeseguin@gmail.com>, Michal Papis <mpapis@gmail.com> [https://rvm.beginrescueend.com/]

Bundler Version

builder (3.0.0)
bundler (1.0.21)

LOCAL GEMS after installed Rails 3.1.3

*** LOCAL GEMS ***

actionmailer (3.1.3)
actionpack (3.1.3)
activemodel (3.1.3)
activerecord (3.1.3)
activeresource (3.1.3)
activesupport (3.1.3)
arel (2.2.1)
builder (3.0.0)
bundler (1.0.21)
erubis (2.7.0)
hike (1.2.1)
i18n (0.6.0)
json (1.6.5)
mail (2.3.0)
mime-types (1.17.2)
multi_json (1.0.4)
polyglot (0.3.3)
rack (1.3.6)
rack-cache (1.1)
rack-mount (0.8.3)
rack-ssl (1.3.2)
rack-test (0.6.1)
rails (3.1.3)
railties (3.1.3)
rake (0.9.2.2)
rdoc (3.12)
sprockets (2.0.3)
thor (0.14.6)
tilt (1.3.3)
treetop (1.4.10)
tzinfo (0.3.31)

Unicorn Version

unicorn (4.1.1)

All Gems installed
actionmailer (3.1.3)
actionpack (3.1.3)
activemodel (3.1.3)
activerecord (3.1.3)
activeresource (3.1.3)
activesupport (3.1.3)
addressable (2.2.4)
ansi (1.4.1)
arel (2.2.1)
aws-s3 (0.6.2)
bcrypt-ruby (2.1.4)
builder (3.0.0)
bundler (1.0.21)
cocaine (0.2.1)
coffee-script (2.2.0)
coffee-script-source (1.2.0)
colorize (0.5.8)
daemons (1.1.5)
delayed_job (2.1.4)
devise (1.4.2)
diff-lcs (1.1.3)
erubis (2.7.0)
execjs (1.2.6)
faraday (0.6.1)
hashie (1.2.0)
hike (1.2.1)
hoe (2.12.5)
i18n (0.6.0)
jquery-rails (1.0.14)
json (1.6.5)
kaminari (0.12.4)
kgio (2.7.2)
libv8 (3.3.10.4 x86-linux)
machinist (2.0.0.beta2)
mail (2.3.0)
metaclass (0.0.1)
mime-types (1.17.2)
mocha (0.10.0)
multi_json (1.0.4)
multi_xml (0.2.2)
multipart-post (1.1.4)
mysql2 (0.3.6)
net-ldap (0.2.2)
newrelic_rpm (3.3.0)
nifty-generators (0.4.6)
nokogiri (1.4.7)
oa-basic (0.2.6)
oa-core (0.2.6)
oa-enterprise (0.2.6)
oa-more (0.2.6)
oa-oauth (0.2.6)
oa-openid (0.2.6)
oauth (0.4.5)
oauth2 (0.4.1)
omniauth (0.2.6)
orm_adapter (0.0.6)
polyglot (0.3.3)
pyu-ruby-sasl (0.0.3.3)
rack (1.3.6)
rack-cache (1.1)
rack-mount (0.8.3)
rack-openid (1.3.1)
rack-ssl (1.3.2)
rack-test (0.6.1)
rails (3.1.3)
railties (3.1.3)
raindrops (0.8.0)
rake (0.9.2.2)
rdoc (3.12)
rest-client (1.6.7)
riddle (1.5.1)
rspec (2.6.0)
rspec-core (2.6.4)
rspec-expectations (2.6.0)
rspec-mocks (2.6.0)
rspec-rails (2.6.1)
ruby-openid (2.1.8)
ruby-openid-apps-discovery (1.2.0)
rubyntlm (0.1.1)
sass (3.1.12)
sass-rails (3.1.2)
sprockets (2.0.3)
SyslogLogger (1.4.0)
therubyracer (0.9.4)
thinking-sphinx (2.0.10)
thor (0.14.6)
tilt (1.3.3)
treetop (1.4.10)
ts-delayed-delta (1.1.2)
turn (0.8.2)
tzinfo (0.3.31)
uglifier (1.0.3)
unicorn (4.1.1)
warden (1.0.6)
wkhtmltopdf (0.1.2)
xml-simple (1.1.1)

Two ways to load files in Rails

There are two ways that files get loaded in Rails:

It is registered in the autoload process, and you reference a constant that corresponds to the file name. For instance, if you have app/controllers/pages_controller.rb and reference PagesController, app/controllers/pages_controller.rb will automatically be loaded. This happens for a preset list of directories in the load path. This is a feature of Rails, and is not part of the normal Ruby load process.
Files are explicitly required. If a file is required, Ruby looks through the entire list of paths in your load paths, and find the first case where the file you required is in the load path. You can see the entire load path by inspecting $LOAD_PATH (an alias for $:).

Since lib is in your load path, you have two options: either name your files with the same names as the constants, so Rails will automatically pick them up when you reference the constant in question, or explicitly require the module.

I also notice that you might be confused about another thing. ApplicationController is not the root object in the system. Observe:

module MyModule
  def im_awesome
    puts "#{self} is so awesome"
  end
end

class ApplicationController < ActionController::Base
  include MyModule
end

class AnotherClass
end

AnotherClass.new.im_awesome
# NoMethodError: undefined method `im_awesome' for #

You will need to include the module into whatever class you want to use it in.

class AnotherClass
  include MyModule
end

AnotherClass.new.im_awesome
# AnotherClass is so awesome

Of course, in order to be able to include the module in the first place, you’ll need to have it available (using either of the techniques above).

Reference: This note is from a blog/site that I looked for some knowledge.

Get information about your Rails Environment

To get information about your Rails Environment Rails, Ruby, Rack versions use the following command,

$ rake about

About your application's environment
Ruby version 1.9.2 (i686-linux)
RubyGems version 1.8.10
Rack version 1.3
Rails version 3.1.3
JavaScript Runtime therubyracer (V8)
Active Record version 3.1.3
Action Pack version 3.1.3
Active Resource version 3.1.3
Action Mailer version 3.1.3
Active Support version 3.1.3
Middleware Rack::Cache, ActionDispatch::Static, Rack::Lock, Rack::Runtime, Rack::MethodOverride, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::RemoteIp, Rack::Sendfile, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, ActionDispatch::ParamsParser, ActionDispatch::Head, Rack::ConditionalGet, Rack::ETag, ActionDispatch::BestStandardsSupport, Warden::Manager, OmniAuth::Builder
Application root /home/abhi/my_app
Environment development
Database adapter mysql2
Database schema version 20120704103548

Rails Console ‘sandbox’ to test your rails application data

We know that how useful the rails console is. We can access the database and manupulate the data, but if you wish to test out some code without changing any data of your database, you can use sandbox option rails console –sandbox.

$ rails console --sandbox
Loading development environment in sandbox (Rails 3.1.0)
Any modifications you make will be rolled back on exit
irb(main):001:0>

How is it?

Ruby string method ‘scan’

Here I am writing about the ruby scan method for string.

syntax: scan(pattern) => array

Take a string name, where

irb> name = "Viswanathan Anand"

You scan through the string for words by,

ruby-1.9.2-p290 :014 > name.scan(/\w+/)
 => ["Viswanathan", "Anand"]

scan for 3 letters and make them an array element,

ruby-1.9.2-p290 :015 > name.scan(/.../)
 => ["Vis", "wan", "ath", "an ", "Ana"]

scan for 3 letters and group them with an array and make them array element,

ruby-1.9.2-p290 :016 > name.scan(/(...)/)
 => [["Vis"], ["wan"], ["ath"], ["an "], ["Ana"]]

and you can make three two pair letters in an array like:

ruby-1.9.2-p290 :017 > name.scan(/(...)(...)/)
 => [["Vis", "wan"], ["ath", "an "]]

You can also use reg exp like,

ruby-1.9.2-p290 :018 > name.scan(/[A-Z][a-z]+/)
 => ["Viswanathan", "Anand"]

Rails MemCacheStore and dalli gem

We can use a memcached server for centralized caching in our application. This server is handling all caching mechanisms. Rails is using the gem memcache-client by default. But here I am using the dalli gem. Because it is better than memcache-client, but one thing to say is I am not experienced this. By reading documents, I have concluded that. You just go through this dalli gem link, https://github.com/mperham/dalli. This is a super caching mechanism by Rails in production environments. The Only thing we need to do is

  1. Say you want caching in your application, by adding the following in your environments, add the following in your production.rb file, if you are running in production mode and you are using production.rb file as your environment configuration file.
    2. config.action_controller.perform_caching = true
  2. Just install dalli gem

    3. Add the following in your gem file and do bundle install

    $ gem 'dalli', '2.0.2'
$ bundle install
  3. Install memcached server
    4. $ sudo apt-get install memcached
  4. Start the memcached server if not started
    5. $ sudo /etc/init.d/memcached start
  5. Configure in your environments, add the following in your production.rb file 
    6. config.cache_store = :dalli_store, 'YOUR_PRODUCTION_PUBLIC_DNS:11211',
    { :namespace => "app-YOUR_HOST", :expires_in => 1.day, :compress => true }

    Here ‘YOUR_PRODUCTION_PUBLIC_DNS:11211’ is saying where your memcached server is running. Public DNS and the port number of the memcached server.

Take the rails console and experiment something like the following to know the MemCacheStore cache mechanism is working. If you are in localhost then do

ruby-1.9.2-p290 :003 > cache = Dalli::Client.new('localhost:11211')
 => #0}, @ring=nil> 
ruby-1.9.2-p290 :004 > cache.set('testing', 1234)
 => true
ruby-1.9.2-p290 :006 > cache.get('testing')
 => 1234

Now you are ready to go