Z dniem 22 marca 2013 weszła w życie nowelizacja Prawa Telekomunikacyjnego (http://www.dziennikustaw.gov.pl/DU/2012/1445), która jest bezpośrednim skutkiem konieczności dostosowania prawa polskiego do wytycznych Parlamentu Europejskiego – podobne zmiany zaszły, bądź zajdą wkrótce w pozostałych krajach UE.

Najbardziej istotną zmianą z punktu widzenia przedsiębiorców działających w branży WEBowej, jest konieczność pozyskiwania zgody na wykorzystywanie plików cookies na stronach internetowych (art. 173). Użytkownik może wyrazić zgodę przez zastosowanie odpowiednich ustawień w przeglądarce, jednak wtedy strona internetowa wykorzystująca ciasteczka ma obowiązek poinformować internautę o ich stosowaniu i przedstawić politykę ich przetwarzania.

W związku z opisanymi zmianami, warto dodać do wszystkich swoich Railsowych aplikacji stosowne procedury sprawdzające stosowanie plików cookie, zwłaszcza jeśli korzystamy w projektach z autoryzacji użytkowników poprzez np. Devise.

Tutaj http://clearcove.ca/2009/09/rails-cookie-detection/ znajduje się prosty moduł, który moża wykorzystać do wyświetlenia stosownego komunikatu, np.

Ta witryna używa plików cookie. Więcej informacji o używanych przez nas plikach cookie, ich zastosowaniu i sposobie modyfikacji akceptacji plików cookie, można znaleźć tutaj oraz w stopce na naszej stronie internetowej (Polityka plików cookie).

I have recently switched from Ubuntu to Win8 as my basic system. As RoR development under Win is a suicidal practice, I have decided to install Ubuntu on virtual machine (Oracle VM Box).

I want the guest Ubuntu network services (in particlar, LAMP&Rails server services) to be visible for host + guest OS should have access to the internet. Luckily, VirtualBox provides an easy method to accomplish this target in a few steps using secondary host-only network interface.

1. Install guest OS using default NAT network interface.
2. Keeping the VM turned off, configure according to your preferences the host-only network interface in VirtualBox (File->Preferences->Network in VirtualBox main window). Then add the host-only adapter as a secondary network interface for guest OS.
3. Configure guest OS to use static IP on secondary network interface.
4. Edit hosts file in host OS. In case of Windows 8, open notepad as administrator and edit %systemroot%\system32\drivers\etc\hosts appending the following line (GUEST_IP MOCK.DOMAIN) as in the example below:

   192.168.52.101 greg.or
   

Now you can easily access the guest network services (WWW, SSH, FTP etc.) from your host OS. You can find a comprehensive description of the host-only network layer provided by VirtualBox on slides published by Alex Hahn.

I am currently working on the eCommerce project motociclisti.pl based on Spree – „the world’s most flexible eCommerce platform”, as they advertise

Motivation

I needed some tool to manage static pages – like contact, terms of use, some promo-pages etc. Eventually, I’ve decided to go for spree_essential_cms developed by  Spencer Steffen & Citrus. What I was missing there, was the tool to manage menus. So it was time to add some gem to spree community

I have developed spree_essential_menus gem, which smoothly integrates with spree > 1.0.0 and spree_essential_cms > 0.3.0.

Installation

Add the following line to your gemfile:

gem 'spree_essential_menus' 

Then run bundle.

Copy the migrations to your app (yeah, I know, I should add it to extension generator for the future):

bundle exec rake railties:install:migrations

and in the end run rake db:migrate. You are ready to play!

Usage

The SpreeEssentialMenus extension adds a subtab Menus to spree_essential tab (usually Static content, depending on you translation). You should first create Menu bars that you need for your shop (usually main menu and footer menu, but can be infinitely many).

Then in every menu bar, you can create as many menu elements as you want to.

You have two options:

• manually type the path (it can be both relative or absolute, but in case of aboulute path remember to start with „http://”)
• select a static page created in spree_essential_cms, that the menu element should point to. In this case, the path will be filled in automatically.

How to rearrange menu elements?

The menu elements can be easily reorganized by drag&drop functionality – just click on green arrows left to the element’s name in the index page of selected menu bar’s elements and drag it where you want to.

How to embedd it in my layout?

When you create Menu bars, you can easily embedd them in your layout by the partial, like below (written in HAML):

%header
  %nav
    - @menu_bar = Spree::MenuBar.find_by_name("main_menu")
    = render :partial => "spree/shared/render_menu", :locals => {:menu_bar => @menu_bar}

So far, 3 different menu presentations are available:

• render_menu – standard menu
• render_image_menu
  
  
• render_scroll_menu
  
  

Nested structure

Recently I’ve also added a nested_set structure for menu_elements. So for every menu element you can select a parent (within the same menu_bar), and thus create a nested menu with submenus.

Issues

So far I do not know any – if you find one, please report on GitHub – https://github.com/matfiz/spree_essential_menus

Feel free to pull and contribute I hope it will be usefull!

A client wanted to export some tabular data from the database to an editable format, so xls was an obvious choice. Before I mastered the export of the same piece of data into pdf format using Prawn gem, now I want to present you an easy way to achieve fairly the same effect, but in Excel output.

Let’s assume we have a list of clients in an array clients:

In order to export data to Excel, we will use the Ruby spreadsheet gem (project’s page: http://spreadsheet.ch/ and at Rubygem: http://rubygems.org/gems/spreadsheet). The gem provides a flexible way to manipulate, import and export xls data.

1. First, we need to register new mimetype – xls.
   Let’s create config/initializers/mime_types.rb and paste:

   Mime::Type.register 'application/vnd.ms-excel', :xls
   

2. Next, we have to extend the selected controller’s action to respond to xls

   def index
     @clients = Client.all
     require 'spreadsheet'
     respond_to do |format|
         format.pdf
         format.xls {
           clients = Spreadsheet::Workbook.new
           list = clients.create_worksheet :name => 'List of cliets'
           list.row(0).concat %w{Name Surname Age}
           @clients.each_with_index { |client, i|
              list.row(i+1).push client.name,client.surname,client.age
           }
           header_format = Spreadsheet::Format.new :color => :green, :weight => :bold
           list.row(0).default_format = header_format
           #output to blob object
           blob = StringIO.new("")
           clients.write blob
           #respond with blob object as a file
           send_data blob.string, :type => :xls, :filename => "client_list.xls"
         }
   end
   

3. In the end, we can create a link in the view: link_to clients_path(:format => :xls)
4. Click the link and enjoy the xls being downloaded. Remember you can style and/or add additional worksheets to your Excel workbook – refer to spreadsheet manual if needed.

I have just shown a Turnkey Linux Rails (VirtualBox edition) to my RoR developer friend. He really enjoyed using it, however after a few days he mentioned that he had a problem – every time he moved his laptop to a different network, he needed to restart Linux in orded to detect the proper IP through bridged network card connection. This is a distinct loss of time!

There is a simple command to renew (restart, or rather reflush) the ethernet connection, that will result in the renewing of DHPC IP. Assuming your network connection is eth0 (you can check it with ifconfig command), just type:

ifdown eth0
ifup eth0

And that’s all! The new IP would be printed in the output of the last command.

Recently I have worked on project that needed a pdf form to be filled with data gathered in Rails3 app db.

As I have decided to use PRAWN as a PDF generator (with prawn_rails gem – I can really recommend, works with Rails3), I had to choose between recreating the form or just filling in the form that was ready. As time=money, I decided to go for the second possibility.

1. I converted the pdf form to JPG (300 dpi resolution, no compression).

2. I needed A4 page size, so I also need to scale my image. In my example_document.pdf.prawn, I should put:

bg = "#{RAILS_ROOT}/public/pdf/pdf_bg.jpg"

prawn_document (
    :filename=>'foo.pdf',
    :page_size=> "A4",
    :margin => 0) do |pdf|
      pdf.image bg,
        :at  => [0, Prawn::Document::PageGeometry::SIZES["A4"][1]],
        :fit => Prawn::Document::PageGeometry::SIZES["A4"]
  pdf.text "This is pdf with background image ready to fill in"
end

The code above imports the image and positions it in the right left corner (remember! bounding box in pdf has its origin [0,0] in BOTTOM LEFT corner of the page). The size of A4 is set as constant by PRAWN (nice of them, isn’t it?). You can access it by Prawn::Document::PageGeometry::SIZES array. The full list of available page sizes you can find in PRAWN source code at https://github.com/sandal/prawn/blob/master/lib/prawn/document/page_geometry.rb.

3. Now one has to play around a little bit in order to position the data obtained from db in right positions.

Good luck!

1. I was trying to add a gem to a Rails3 app gemfile directing it to a git repo by:

gem 'example', :git => "git://github.com/gituser/example.git"

While bundle install, I got the error message:

fatal: Unable to look up github.com (port 9418) (Name or service not known)

I tried git clone -q git://github.com/gituser/example.git or rails plugin install git://github.com/gituser/example.git, still I got the same error message. It seems that Github has recently updated DNS and the changes haven’t propagated yet. You can use a workaround:

1. Run ping github.com and read the current IP
2. Go to /etc/hosts on your Rails server (assuming its Linux) and add the following line:

   207.97.227.239 github.com wiki.github.com gist.github.com assets0.github.com assets1.github.com assets2.github.com assets3.github.com
   

   where instead of 207.97.227.239 type it the current Github IP

It is suggested to remove this line once the DNS is up and working again.

Source

After recent update of RubyGems (to 1.8), while running for example bundle install, the user will see a bunch of warnings, like:

NOTE: Gem::Specification# default_executable = is deprecated with no replacement. It will be removed on or after 2011-10-01.

This is connected with the recent policy of RubyGems team – read the official statement.

They have deprecated 22+ methods! It will take some time for Gem authors to update… Before then, you may run:

gem pristine --all --no-extensions

to get most recent and thus some of the warrnings gone…

Since Rails3 is quite popular right now, many programmers move their projects to this version. So did I However, because of some major bugs in Ruby 1.8.7, Rails3 needs Ruby >=1.9.1. The problem is that I still have to maintain some Rails 2.3.5 projects…

There is a solution: Ruby Version Manager (RVM)… but not for windows For the latter, you should use PIK gem https://github.com/vertiginous/pik. The installation is pretty easy, just follow the tutorial at github repo step by step.

PROBLEM

So install PIK, add all ruby versions you want to, use the one you need. But well, life is not that easy… Supposing you’ve got some more complicated gem dependencies in your gemfile, when you try to run:

rake db:migrate

you will probably see the message like below:

There was an error. Error - can't dup NilClass /gemname/

or, in case you use sqlite3:

Unknown method sqlite3_backup_finish in sqlite3.dll.

SOLUTION

1. Set gem_home for the choosen ruby version. Probably the path to install gems isn’t set to unique for every Ruby version you’ve installed. This may be highly confusing and cause some errors if you use different gem versions for Rails 2.3.x and Rails3 (which is the case in 99% of cases).

• Supposing you work on Ruby 1.9.2, you type: pik use 192.
• Then you can check where is current working dir: which ruby or which rails.
• Go to c:/Users/username/.pik/config.yml.
• Edit the proper line in YAML file adding the following lines to the chosen Ruby version

  :gem_home: !ruby/object:Pathname
      path: c:/users/greg/.pik/rubies/Ruby-192-p180
  

  So that the whole version definifion will look like:

  "192: ruby 1.9.2p180 (2011-02-18) [i386-mingw32]":
    :gem_home: !ruby/object:Pathname
      path: c:/users/greg/.pik/rubies/Ruby-192-p180
    :path: !ruby/object:Pathname
      path: C:/Users/Greg/.pik/rubies/Ruby-192-p180/bin
  

  Mind the spaces and tabs!

2. SQLite 3 for Windows needs some additional libraries. You can find them at http://www.sqlite.org/download.html The solution is simple: download the sqlite3.dll and sqlite3.exe and copy it to your Ruby bin directiory, i.e. C:/Users/Greg/.pik/rubies/Ruby-192-p180/bin

I hope this was helpful and saved you some time of your life

Defining a string in Ruby is pretty simple:

s1 = 'Hello!'
s2 = "This is a string.\n Calculations: 2+2=#{2+2}"

You can use both single and double quotes, however double quotes give you much more – expressions enclosed in #{} would be processed by Ruby before string is shown. Pretty cool, heh?
But I am sure most of you have already known that. Let’s proceed than: consider you have a string, that contains many mixed quotes (‚) and double quotes („). How to write it, if the same marks (‚) and („) are considered as string delimiters? Of course you can concatenate string step by step delimiting single quote with double quoted and vice versa, but this is painful. There is a better solution:

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