Panos Matsinopoulos

Senior Software Engineer: Love Creating Software, Taking Entrepreneurial Risks, Teaching Computer Programming & Blogging here or in many other places


My Contact Details


My Books


My Projects

Rails Params Does the Job

| Comments

When you have a Ruby on Rails end point, the client usually sends data in one of the following:

  1. For GET requests, URL encoded in the URI
  2. For POST requests, in the body of the request encoded with application/x-www-form-urlencoded or application/json or other popular format.

Sometimes, there is a combination of the above methods. In other words, in a POST request, some of the data may come both URL encoded in the URI and other data may come encoded with another method in the body of the request.

Ruby Array Sum

| Comments

This short post is going to demonstrate how we can sum an array of integers or an array of objects that have an integer attribute.

Let’s start:

Class vs Instance Variables

| Comments

demo of Class vs Instance variables
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
# Here, I am defining a class Dog with an class variable "@@number_of_feet"
# and an instance variable "@color", assuming that all dogs in the world
# have the same number of feet but they might differ in color. Or, at least,
# this is the general rule.
#
class Dog
  @@number_of_feet = 4

  def initialize(color)
    @color = color
  end

  def number_of_feet=(value)
    @@number_of_feet = value
  end

  def tell_me_about_you
    puts "My color is #{@color} and I have #{@@number_of_feet} feet"
  end
end

# The next two statements will set the "@color" instance variable to different values
# for max and rocky. But both dogs will have the same number of feet, which will be 4,
# since when class is initialized the "@@number_of_feet" instance variable takes the value 4.

max = Dog.new('black')
rocky = Dog.new('brown')

max.tell_me_about_you    # will print black and 4
rocky.tell_me_about_you  # will print brown and 4

# Now, I am changing the value of the class variable "@@number_of_feet" and I am setting that
# to "3". You will see that now all dogs change to have 3 feet.
max.number_of_feet = 3

max.tell_me_about_you    # will print black and 3
rocky.tell_me_about_you  # will print brown and 3

United States, Counties, Cities, Zips CSV & Ruby Loading Code

| Comments

I just wanted to have the United States, their Counties, the Cities in the Counties and the Zip codes in each City in CSV format. But I wanted that normalized. In different CSVs. So, here it is. You can also find here some Ruby on Rails sample code that loads these files. Primitive stuff, but sometimes useful.

My sponsor on that is Book&Table
I am about to start a Seminar: Introduction to Programming. If you are interested in, register here.

Using String Column Type for Migrations

| Comments

Ruby on Rails migrations are used to create the necessary tables inside our database. One of the most frequently used column type is string. Here is an example of an ActiveRecord::Migration that uses this type:

The Clean Coder - a Code of Conduct for Professional Programmers - R. Martin (Pearson)

| Comments

I have recently finished the book “The Clean Coder - A Code of Conduct for Professional Programmers - R. Martin (Pearson, 2011) BBS”. Here is my short review:

Overall: Fantastic. Worth reading for every developer that wants to become professional.

My Notes and Highlights

Chapter 1 - Professionalism

  • Professionalism is a marker of responsibility and accountability.
  • It is better to make your manager unhappy rather than your manager customers.

Twitter Bootstrap 2 Modal Scrolling Problem | Why Capybara/selenium Cannot Locate Your Visible Buttons

| Comments

Twitter Bootstrap 2 has a bug while on modal dialogs. The page does not scroll as expected. So, if the browser window is not wide/tall enough to display the whole modal dialog content, the scroll bars do not make it appear.

The bug is described here:

And the answer is given a little bit below that:

This problem does not occur with jQuery modals neither with Twitter Bootstrap 3.

I am using Ruby on Rails and the less-rails-bootstrap gem.

In order to fix the problem for my current application, and instead of moving to Twitter Bootstrap 3 or to jQuery, I have decided to fix the problem in the gem

Here is the fix:

gem 'less-rails-bootstrap', :git => 'https://github.com/pmatsinopoulos/less-rails-bootstrap.git', :branch => 'bug-fix-modal-scrolling'

Important Note This bug influences your capybara/selenium tests, because elements that are normally visible, while the browser is maximized, they cannot be located by selenium and they are reported as non-visible and cannot be interacted with, if the window browser is not open enough to display the whole modal dialog.

Model Properties - Styling

| Comments

I usually come across people asking what is the preferred way of laying out the properties of a model and, in fact, of an ActiveRecord model. Shall we put first the validations and then the associations? Or first the associations and then the validations? Or shall we put first the callbacks?

One can google for rails style guide. Will basically find only this:

which is a good resource. But is not complete.

My Rails Model Style Guidelines

we are talking here about Rails 3

Here is the list of my styling guidelines and which I use whenever I am writing a Model.