Today I Learned (TIL)

This is a growing collection of random things that I've picked up over time and don't want to forget. There is no organisation or coherence to it all. It's just a list. It's messy. But it's mine :) More recently I've been collecting these in Notion because it's easier to manage.

• rails console -- --nomultiline
• printenv
• ~/.irbrc
• irb measure - https://jemma.dev/blog/irb-measure
• rspec –only-failures
• the difference between transform & resolve. transform can happen with nothing more than input -> output. but rest
• set VSCODE as git editor: git config --global core.editor "code --wait"

SELECT  object_id, index_id, COUNT(*) OVER ()
FROM    [msdb].sys.indexes;

• use result of last command $(!!)

  • bundle show gemname. results in # /path/to/gem
  • code $(!!) opens /path/to/gem in vscode

• If chrome basic auth is sticking (no prompt) run this chrome://restart

• .gitattributes

  • touch ~/.gitattributes

    *.rb diff=ruby
    *.rake diff=ruby

• OODA - for problem solving

  • observe
  • orient
  • decide
  • act

• xargs: ls*/log/**log | xargs rm

select * from generate_series(
'2020-01-01'::DATE,
'2021-01-01'::DATE,
'1 DAY'
)

• rails db - shortcut for database specific cli: psql or mysql
• heroku pg:upgrade - not as scary as i thought!
• grep —context=8 "search" file.txt
• Give localhost network alias so that docker container can connect
  • sudo ifconfig lo0 alias 10.254.254.254
• create an ARCHITECTURE.md file
• z shell navigation "autocomplete" but better! https://github.com/rupa/z
• all about bash scripts. too much to list. will need to revisit this regularly.
• bc command. basic calculator. pipe calculator expressions to do basic math
  • echo "12+5" | bc
  • 17
• fish shell, create abbreviation:
  • abbr gp git pull
  • now gp is alias to git pull
• pbcopy copy command line to
• rails stats
• speed up rubocop
  • https://docspring.com/blog/posts/making-rubocop-20-times-faster/
• SQL: ceil(random() * 3) is better than round(random() * 3) because distribution is more even

WITH daterangeAS (
SELECT *
FROM generate_series(
        '2021-01-01'::timestamptz,-- start'2021-01-02'::timestamptz,-- stopinterval '1 hour'-- step    )WITHORDINALITYAS t(hh, n)
)SELECT *FROM daterange;

• postgresql equivalent of mysql's "insert ignore"

  • insert into table (column) values ('value') on conflict do nothing.

• Rails wildcard routes can contain multiple parameters. I'm not sure why this wasnt' obvious to me before? I guess I've only ever used one at a time. "*a/route/*b" params[:a] params[:b]

• which -a executable : will show all options, not just the first

• console.log({width}) is equivalent to console.log('width', width)

• "Weeks of coding can save you hours of planning"

• Rails render collection

  • https://thoughtbot.com/blog/rendering-collections-in-rails

• https://avdi.codes/throw-catch-raise-rescue-im-so-confused/

• Hash.invert - takes a hash and returns a new hash with keys as values and values as keys

  • { a: 1 }.invert → { 1: a }

  # does what it says. creates a helper method from a method in the application_controller
  def current_user
    @current_user ||= User.find(cookies.signed[:user_id])
  end
  helper_method :current_user

• https://til.hashrocket.com/posts/f4agttd8si-chaining-then-in-ruby-26

• Cmd-K on github

• ssl rails server → https://gist.github.com/trcarden/3295935

• “show data_directory” - postgres/psql

• http://localhost:3000/rails/info/routes show rails routes in browser

• https://hstspreload.org

• fix postgres serial sequence when it goes out of date

  • SELECT nextval('discounts_id_seq'); # check existing sequence
  • SELECT SETVAL('public."discounts_id_seq"', COALESCE(MAX(id), 1)) FROM public."discounts";

• how to edit directly in github

• ditto

• how to fake git commit date