There are many different methods that allow mapping an Array to a Hash in Ruby.

Enumerable#index_by (any Rails)

users = User.all
users_by_id = users.index_by(&:id)

{
  1 => #<User id: 1, name: "Alice">,
  2 => #<User id...

Find conditions for scopes can be given either as an array (:conditions => ['state = ?', 'draft']) or a hash (:conditions => { 'state' => 'draft' }). The later is nicer to read, but has horrible security implications in some versions of Ru...

tl;dr: Do not use merge! for session hashes. Use update instead.

Outline

Let's assume you're modifying the Rails session. For simplicity, let's also assume your session is empty when you start (same effect when there is data):

# In o...

"Everything in Ruby is an object". This is also true for nested hashes and arrays. If you copy a hash with #clone or #dup and you modify the copy, you will run into the following behavior:

original_hash = { foo: { bar: 'original value...

Slides for Henning's talk on Sep 21st 2017.

Understanding sync vs. async control flow

Talking to synchronous (or "blocking") API

print('script start')
html = get('/foo')
print(html)
print('script end'...

Preparation

To attach files to your records, you will need a new database column representing the filename of the file. To do this, add a new migration (rails g migration <name>) with the following content:

class AddAttachmentToNotes...

Rails flashes (FlashHash) track a list of used keys, which is not respected when comparing flash hashes.

This does not concern you under most circumstances.

Basics

When ActionController picks up a flash object, it will call the #sweep m...

TL;DR Avoid before(:context) (formerly before(:all)), use before(:example) (formerly before(:each)) instead.

If you do use before(:context), you need to know what you are doing and take care of any cleanup yourself.

Why?

...

The issue in this card can occur if the node_modules directory is checked into your Git repository. We usually recommend to exclude node_modules from version control.

In any case you should document which version of node to use in your pr...

Rails has always included a scaffold script that generates a default controller implementation for you. Unfortunately that generated controller is unnecessarily verbose.

When we take over Rails projects from other teams, we often find that cont...