ruby

Difference between rake db:migrate db:reset and db:schema:load

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db:migrate runs (single) migrations that have not run yet. db:create creates the database db:drop deletes the database db:schema:load creates tables and columns within the existing database following schema.rb. This will delete existing data. db:setup does db:create, db:schema:load, db:seed db:reset does db:drop, db:setup db:migrate:reset does db:drop, db:create, db:migrate Typically, you would use db:migrate after having made … Read more

Execute a command line binary with Node.js

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For even newer version of Node.js (v8.1.4), the events and calls are similar or identical to older versions, but it’s encouraged to use the standard newer language features. Examples: For buffered, non-stream formatted output (you get it all at once), use child_process.exec: const { exec } = require(‘child_process’); exec(‘cat *.js bad_file | wc -l’, (err, … Read more

How to generate a random string in Ruby

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(0…8).map { (65 + rand(26)).chr }.join I spend too much time golfing. (0…50).map { (‘a’..’z’).to_a[rand(26)] }.join And a last one that’s even more confusing, but more flexible and wastes fewer cycles: o = [(‘a’..’z’), (‘A’..’Z’)].map(&:to_a).flatten string = (0…50).map { o[rand(o.length)] }.join If you want to generate some random text then use the following: 50.times.map { … Read more

Multi-Line Comments in Ruby?

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#!/usr/bin/env ruby =begin Every body mentioned this way to have multiline comments. The =begin and =end must be at the beginning of the line or it will be a syntax error. =end puts “Hello world!” <<-DOC Also, you could create a docstring. which… DOC puts “Hello world!” “..is kinda ugly and creates a String instance, … Read more

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