Learning Ruby On Rails: Day 10

Morgan Fogarty
Oct 29, 2018 · 3 min read
Image for post
Image for post
“Black and Blue: The Invisible Man and the Masque of Blackness” Artist: Zak Ové

In an attempt to learn more, faster, I’m changing the style of these posts a little. I’ll be sharing notes, rather than creating micro tutorials of what I’ve learned each day.

  • Action Pack: the Controller and View Rails component.
  • We generate dynamic content in our views with Embedded Ruby (erb).
  • Ruby is an object oriented programming language.
  • Local variables, method names and method parameters should all start with a lower case letter or underscore.
  • Instance variables begin with an @.
  • Use underscores to separate words.
  • Class names are capitalized and CamelCased.
  • Symbols are string literals magically made into constants.
  • Everything in Ruby is an object.
  • Double quotes are used for expression interpolation, and for strings that have single quotes in them. Example: "Let's hang out".
  • Arrays are ordered collections of things. To reference an item in an array, you use an item’s index (which is an integer). Example: array_of_things[0].
  • Hashes are collections of key/value pairs. To reference an item in a hash, you use its key (which can be a symbol or string). Example: hash_of_things[:some_key].
  • nil is an object.
  • The << method is used to append a single value to the end of an array.
  • Hashes have keys and values.
  • The keys can be a symbol, string, or a variable that returns a symbol or string.
  • The syntax to separate a key from its value is always a hashrocket (=>).
  • The one allowed exception to this rule is if the key is a symbol, in which case the symbol can be immediately followed (no space) by a colon. And then a space.
  • That said, a symbol as a key is still allowed to use a hash rocket. (In which case the symbol’s colon goes at the start of the symbol, not the end.)
  • The colon separator is completely optional and is syntactical sugar. (ie, it’s nice and cleaner, but not required.)
  • unless is like if but it checks for the condition not to be true.
  • until is like while, but it continues until the condition evaluates to true.
  • We can put the if/unless at the end of a line of code instead of wrapping the line of code in an if/unless block. Like this:
puts “danger will Robinson” if radiation > 3000
  • Two organizations for methods: classes and modules.
Class Order < ApplicationRecord

In the above code snippet:

  • Order inherits all behavior from ApplicationRecord.
  • has_many is a method defined by ActiveRecord. It is called as the Order class is being defined.
  • Prefixing a method with self makes it a class method. So it can be called anywhere on the class, instead of on an instance of that class.
  • So I could write:to_collect = Order.find_all_unpaid instead of:@order = Order.new and then: @order.find_all_unpaid.


Next post, here.

Welcome to a place where words matter. On Medium, smart voices and original ideas take center stage - with no ads in sight. Watch

Follow all the topics you care about, and we’ll deliver the best stories for you to your homepage and inbox. Explore

Get unlimited access to the best stories on Medium — and support writers while you’re at it. Just $5/month. Upgrade

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store