TIL, 2017-07-12, LEFT JOIN

RSpec: Think through when_first_matching_example_defined.
Remember: resource has no index–routes for Rails.
ActiveRecord::Base.clear_all_connections! and ActiveRecord::Base.connection.query_cache.clear to clear AR cache.
Problem with putting changes in rake db:migrate–future developers might run rake db:schema:load or rake db:reset, thus not running the insert scripts. Better to just make a tasks for data migration. Reference
Some cool things: print "." when running the migration scripts. Then puts "All done" when migration scripts are done.
Big ass SQL join:

User
  .select('users.*, buddy_relationships.buddy_id AS is_buddy,
      contact_relationships.receiver_user_id AS is_contact')
  .joins('LEFT JOIN buddy_relationships ON buddy_relationships.buddy_id = users.id')
  .joins('LEFT JOIN contact_relationships ON contact_relationships.receiver_user_id = users.id')
  .where("buddy_relationships.user_id = #{user.id} OR contact_relationships.sender_user_id = #{user.id}")

Time Zones

Time.now: Time on my machine
Time.zone = 'Fiji': Set Time.zone to Fiji.
Time.now: Will still get the system time.
Time.zone.now: Get the current time in that zone.
Time.current: Same.
Time.now.in_time_zone: Same
Date.today: System date
Time.zone.today: Application zone.
Time.zone.tomorrow: Correct tomorrow.
1.day.from_now: Correct tomorrow.

Don’t Use

Time.now
Date.today
Date.today.to_time
Time.parse(...)
Time.strptime(...)

Use

Time.current
2.hours.ago
Time.zone.today
Date.current
1.day.from_now
Time.zone.parse...
Time.striptime(...).in_time_zone