Ruby Notes


Yeah, those small details I need to keep looking up as I switch among ruby, javascript, php, and python on any given day.

See also:,_Substitution_and_Insertion

CSV notes at

# remove only leading and trailing whitespace (like PHP's trim) 
# use a regular expression ( this evaluates to 
str = "white chocolate"
str.gsub("white", "dark")
# which are groupings, btw (this evaluates to "1a")
"a1".gsub(/(\w)(\d)/, '\2\1')
# puts and print
print "use a return at the end\n"
puts "automatically adds the newline"

Use bundle to add gems to Gemfile


Similar to npm add module --save to add a node package to the package.json file, you can use bundle to download, install and save a gem to the Gemfile.

bundle add {gem} {version}
# examples
bundle add pdf-reader "2.4"
bundle add pdf-reader 

Install different gems in Docker container


I have a development environment that is used locally within docker containers, and deployed to a Heroku-like environment, which has a different setup than the local Docker setup. When running locally in Docker containers, I want to install debase and the ruby-debug-ide gems, so that I can use RubyMine locally, but these are not needed when deployed to the development instance. The deployment does not use the Docker / docker-compose files, so I'm okay with having them be local-development specific.

The trick I found was to use groups in the Gemfile.

In my Dockerfile, I'd call out the groups with the --with={groups} arguments:

RUN bundler install --with=development,docker

group :docker do
  gem 'debase'
  gem 'ruby-debug-ide'

What gems are installed?


Have a Gemfile or a Gemfile.lock and want to see what versions are installed.

gem list

Ruby Get Instance Name

# controller is whatever object you're looking at

Pretty print a json file


JSON comes over the wire with minimal spaces, making human parsing of the object difficult. The json lib provides an easy way to reformat it into an indented format.

Remember to use #!/usr/bin/env so that any rbenv or rvm specific versions of ruby will be used.

Dump this into a file, say, format-json.rb, and use with:

format-json.rb my-squashed.json > nicely-readable.json


#!/usr/bin/env ruby
require 'json'
exit if ARGV[0].nil?
puts JSON.pretty_generate(JSON.parse([0])))

Dump request into a tmp file


Dump the content of an http request into a /tmp file.

file_name = '/tmp/' + params[:type].gsub(/\./, '_') + '.' + params[:api_version] + '.json', "w+") do |f|

Minitest Cookbook

Book Notes

Okay, so, for the record with this review, The Minitest Cookbook was not the book I needed, nor expected. Take the rest of this review with a grain of salt as a result of that disclaimer.

I've been writing code that is tested with minitest tests for nearly a year now. I find that my understanding of when to use mocks versus stubs versus expects versus pick something else, to be somewhat lacking. Sure, I can cut and paste another test and modify as I need to modify it to fit my particular test case, but I don't want to copy and modify a test. I want to understand the reasoning behind what I'm doing and create a test, to understand "this is what I'm testing and this is how I go about it." Being able to do that quickly requires that I understand the system that I'm working on as a whole perhaps better than I do, but being able to do it without a full understanding is needed at this point.

So, I picked up this book as the recommended minitest book. Lots of favorable reviews, this is the book you want if you're learning minitest.

Except, it isn't.

It's too complicated for beginners (are n00b or newbies still derogatory terms, or have they been embraced by beginners - I guess if beginners are okay with being called dummies, they're okay with being n00bs), and not well organized for an intermediate user. I'd consider myself halfway between those two designations, so figured I'd get it, but, eh, didn't really work out that way.

Agile Web Development in Rails 4

Book Notes

Okay, I read this one again, since the first reading was before I knew what things were and why I was doing things and oh, god, what have I gotten myself into? Helps to have development under your belt for these things.

This book was recommended to me as the book to learn Rails development. It has two main sections: a hands-on let's-build-a-rails-app section, and a here-are-the-explanations section. The first is designed to guide you through building an application with Rails, the second to explain what the hell just happened and how all the parts fit together. The book builds a slight e-commerce platform: a store's product display / catalog, administration section, shopping cart, checkout and user authentication. The example is great, I definitely liked that it wasn't a blog or a twitter client.

The book is good and it works. It is not the book for new developers, however. It uses a lot of words and concepts without explaining them, assuming the reader knows what they mean. And this is okay. The book is for a developer who is learning Rails. It does that well.

Time-wise, if you're going to read the book and do the exercises (say, a new employer is giving you a chance to come up to speed with Rails, or the first couple weeks of work to learn), give yourself 2 work weeks to go through it. You can do it faster (you can always do things faster), but doing the exercises and typing things in and playing around with things relevant-to but not part-of the lessons is what makes learning better. So, yeah, play around, poke around, learn something outside the lesson for greater good.

This would be my Rails Rant of the Day


Okay, I know that using rails is supposed to make one's life easier. I recognize that convention over code rules the rails mindset. I even completely agree that rails devs don't feel pain when they develop applications, with all the various pieces kindly hidden from them. That is great. Good for them / us / me.

But, come on, this?

No, not "come on." More like, "COME THE FUCK ON, WHAT THE FUCKING HELL?"