Keith Schacht’s Weblog

I just learned that ruby supports re-writing this:

total = plus_shipping(with_taxes(subtotal(items)))

As:

subtotal(items).then { |subtotal| with_taxes(subtotal) }.then { |total| plus_shipping(total) } => total

When writing a migration in Rails and you need to do one thing which can’t be automatically reversed, I always convert a def change to up and down. It turns out you can slip in an up_only block:

class AddFieldsToUsers < ActiveRecord::Migration[7.1]
  def change
    add_column :users, :first_name, :string
    add_column :users, :last_name, :string

    up_only do
      User.delete_all
    end
  end
end

In 2028 NASA is launching a spacecraft to Saturn’s moon Titan to study its habitability in a mission named Dragonfly. It will land in 2034. They’re sending a drone powered by a radioisotope thermoelectric generator so they can visit a variety of sites. Titan is notable because it’s believed to have a similar chemistry to ancient earth. Past probes have measured the contents of the atmosphere and confirmed it contains a mix of hydrocarbons. The surface contains a lot of water ice and scientists believe there is a water ocean in the interior of the moon.

I just learned about `sole` and `find_sole_by`. They ensure that only a single record is returned and will raise if there is something other than one. It’s the equivalent of:

api_keys = user.api_keys.where(key: key)

if api_keys.length == 1
  api_key = api_keys.first
elsif api_keys.length == 0
  raise "No records found!"
else
  raise "More than one matching record found!"
end

Instead of doing

Messages.pluck(:user_id).first

Messages.pick(:user_id)