mattlong

Rails dirty

After modifying an object and after saving to the database, or within after_save:

Rails <= 5	Rails >= 5.1
attribute_changed?	saved_change_to_attribute?
changed?	saved_changes?
changes	saved_changes
attribute_was	attribute_before_last_save

mattlong

#!/bin/bash

parents_of_dead_kids=$(ps -ef | grep [d]efunct | awk '{print $3}' | sort | uniq | egrep -v '^1$'); echo "$parents_of_dead_kids" | xargs kill

mattlong

# From https://github.com/rails/rails/issues/20606#issuecomment-113323102
# Almost good, but I don't think it handles the case of promoting an
# existing location to being the primary location correctly in some cases

class Organization < ActiveRecord::Base
  has_many :locations, dependent: :destroy, autosave: true # autosave necessary for the importer
  has_one :primary_location, -> { where(locations: { primary: true }) }, class_name: "Location", autosave: true

  # Override getter to fix issue with Rails not reloading the primary_location after resetting it to nil
  def primary_location

mattlong

http://stackoverflow.com/questions/22667401/postgres-json-data-type-rails-query
http://stackoverflow.com/questions/40702813/query-on-postgres-json-array-field-in-rails

#payload: [{"kind"=>"person"}]
Segment.where("payload @> ?", [{kind: "person"}].to_json)

#data: {"interest"=>["music", "movies", "programming"]}
Segment.where("data @> ?",  {"interest": ["music", "movies", "programming"]}.to_json)
Segment.where("data #>> '{interest, 1}' = 'movies' ")
Segment.where("jsonb_array_length(data->'interest') > 1")

mattlong

module Where
  class <<self
    attr_accessor :editor
    
    def is_proc(proc)
      source_location(proc)
    end
    
    def is_method(klass, method_name)
      source_location(klass.method(method_name))

mattlong

/**
 * Retrieves all the rows in the active spreadsheet that contain data and logs the
 * values for each row.
 * For more information on using the Spreadsheet API, see
 * https://developers.google.com/apps-script/service_spreadsheet
 */
function readRows() {
  var sheet = SpreadsheetApp.getActiveSheet();
  var rows = sheet.getDataRange();
  var numRows = rows.getNumRows();

mattlong

Effective Engineer - Notes

• By Edmond Lau
• Highly Recommended 👍
• http://www.theeffectiveengineer.com/

What's an Effective Engineer?

• They are the people who get things done. Effective Engineers produce results.

Adopt the Right Mindsets

mattlong

-- active connections
SELECT application_name, state, age(now(), xact_start) age, query FROM pg_stat_activity WHERE state <> 'idle';

SELECT application_name, pid, state, age(now(), xact_start) age,
  left(regexp_replace(query,E'[\\n\\r]+',' ','g'), 100)
  FROM pg_stat_activity WHERE state <> 'idle' ORDER BY age;

-- bloated tables
select relname, n_tup_ins, n_tup_upd, n_tup_del, n_tup_hot_upd, n_live_tup,
  n_dead_tup, round(n_dead_tup::numeric/n_live_tup, 2) as bloat,

mattlong

from __future__ import print_function
from sqlalchemy import (
    Column,
    create_engine,
    MetaData,
)
from sqlalchemy.types import String, Integer
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base

mattlong

# From http://stackoverflow.com/questions/17901588/new-repo-with-copied-history-of-only-currently-tracked-files

Delete everything and restore what you want

Rather than delete this-list-of-files one at a time, do the almost-opposite, delete everything and just restore the files you want to keep:

$ git checkout master
$ git ls-files > keep-these.txt
$ git filter-branch --force --index-filter \
  "git rm  --ignore-unmatch --cached -qr . ; \