Category Archives: ruby on rails

Ruby on Rails programming tips

Using Postfix to send out emails from development environment in Rails

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Problem

You want to be able to send emails from your development enironment using Postfix in your (K)Ubuntu pc.

Solution

First you would need to install postfix:

sudo apt-get install postfix

and then you would need to change an option in postfix to not use tls, so change /etc/postfix/main.cf:

sudo vi /etc/postfix/main.cf

and change the smtpd_use_tls from yes to no:

smtpd_use_tls=no

restart your postfix server:

sudo /usr/sbin/postfix reload

and then setup your config/development.rb as follows:

config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
  address:                 "127.0.0.1",
  port:                    25,
  enable_starttls_auto:    false
}

Could not find activesupport-3.0.12 in any of the sources (Bundler::GemNotFound)

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Problem

You are trying to update your rails app deployed on a server, for example from 3.0.11 to 3.0.12, and at the same time trying to update the Ruby version from 1.9.2 to 1.9.3 but you are getting the following error from passenger:

    Could not find activesupport-3.0.12 in any of the sources (Bundler::GemNotFound)

Solution

You would need to reinstall and compile the passenger module with the newest Ruby 1.9.3 installation.


gem install passenger

passenger-install-apache2-module

and then modify the apache configuration file as in:

The Apache 2 module was successfully installed.                   

Please edit your Apache configuration file, and add these lines:

   LoadModule passenger_module /usr/local/rvm/gems/ruby-1.9.3-p125/gems/passenger-3.0.11/ext/apache2/mod_passenger.so
   PassengerRoot /usr/local/rvm/gems/ruby-1.9.3-p125/gems/passenger-3.0.11
   PassengerRuby /usr/local/rvm/wrappers/ruby-1.9.3-p125/ruby

After you restart Apache, you are ready to deploy any number of Ruby on Rails
applications on Apache, without any further Ruby on Rails-specific
configuration!

and then reload your apache configuration

sudo /etc/init.di/apache2 reload

cannot load such file — zlib

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Problemo

You are trying to install a gem with rvm but you are getting the following error:

ERROR: Loading command: install (LoadError
cannot load such file — zlib
ERROR: While executing gem … (NameError)
uninitialized constant Gem::Commands::InstallCommand

Solution

Following from the post here

you would need to install the zlib library with rvm, uninstall your ruby version and then install the ruby version again with the folowing:

 

rvm pkg install zlib

rvm uninstall 1.9.3

rvm install 1.9.3

Adding a record in Rails through javascript

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Problem

You would like to trigger a record insertion after a specific action has happened through javascript (ie drag – drop an item into a container), in a rails application.

 

Solution

You would need to get the object attributes from the html page somehow (ie user_id and user_name), and then have a function in your application js that calls the post function.

So if you have a drag and drop container for example then the code in the application.js should be like the following:

$("#name_of_container").droppable({
  drop: handleDropEvent
});

function handleDropEvent(event,ui) {
  var user_id = ui.draggable.attr("user_id");
  var user_name = ui.draggable.attr("user_name");
  $.post('/users', {user: {user_id: user_id, name: user_name}})
}

 

Replacing mock objects with factory girl in controller rspecs

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Problem

You would like to use factory_girl instead of the mock models described in the RSpec book (Behaviour Driven Rails – Rails Controllers – Controller specs).

 

Solution

Make sure that you use let! instead of let and have the following:

 

require 'spec_helper'

describe MessagesController do
  describe "POST create" do
    let!(:message) { Factory.create(:message) }
    
    before do 
      Message.stub(:new).and_return(message)
    end
    
    it "creates a new message" do
      Messagee.should_receive(:new).with("text" => "a quick brown fox").and_return(message)
      post :create, :message => {"text" => "a quick brown fox"}
    end
    
    it "saves the message" do
      message.should_receive(:save)
      post :create
    end

    it "redirects to the Messages index" do
      post :create
      response.should redirect_to(:action => "index")
    end
  end
end

ERD diagrams in Ruby on Rails

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Problem

You would like to have an ERD diagram of your database in your Ruby on Rails project.

Solution

You can install the Rails ERD from here, and install it by following the instructions.
For Ubuntu/debian systems should be:

sudo apt-get install graphviz

and then adding the gem to your Gemfile in the development section as:

group :development do
  gem "rails-erd", "~> 0.4.5"
end

You can then run bundle install to install the gem and rake erb to create the diagram pdf.

Pausing between steps in cucumber

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Problem

You want to be able to go through a scenario step by step when you are testing with a browser as sometimes can be very fast.

 

Solution

By following the suggestion here you would only need to add the following to your features/support/hooks.rb file

AfterStep('@pause') do
  print "Press Return to continue ..."
  STDIN.getc
end

and then you should be able to use it in your scenario by adding the @pause tag.
Then you would have to press continue in your terminal to go step by step

Using named gemsets with rvm

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Problem

You want to be able to use different gems/rails version for your application after installing the latest rails version, without having to use bundle exec.

 

Solution

You can use the named gemsets with rvm.

More instructions are here: http://beginrescueend.com/gemsets/basics/

so you can install two gemsets for example ruby-1.9.3-p0@rails3_0_11 and another with ruby-1.9.3-p0@rails3_2_1

you could then do :

rvm gemset create rails3_0_11 rails3_2_1

rvm 1.9.3-p0@rails3_0_11
gem install rails -v 3.0.11

rvm 1.9.3-p0@rails3_2_1
gem install rails -v 3.2.1

rvm gemset use rails3_0_11
bundle install

you could then also use some aliases in your ~/.bashrc file to be able to use the gemsets by using only one command as for example in ($ rvm3011):

# Rails 3.0.x
alias rvm3011="rvm gemset use rails3_0_11"
alias rvm3012="rvm gemset use rails3_0_12"

# Rails 3.2.x
alias rvm321="rvm gemset use rails3_2_1"
alias rvm322="rvm gemset use rails3_2_2"