How to print from an iPad.

Sometimes you may want to print files from the command line, especially when you have lots of them.
You can use lp for that.

To print a single example.pdf file on your default printer, simply say:

lp example.pdf

lp accepts multipl...

PostgreSQL's array data type is pretty useful, but manipulating values of arrays can be awkward because of its syntax.

Consider the following users table which each example below will sta...

A print stylesheet is easy to create. Choose a font suited for paper, hide some elements, done. Unfortunately print stylesheets often break as the application is developed further, because they are quickly forgotten and nobody bothers to check if ...

This cards describes an example with a Github Client on how to keep your Rails application more maintainable by extracting domain independent code from the app/models folder to the lib/ folder. The approach is applicable to arbitrary scenarios...

When you need information about a gem (like version(s) or install path(s)), you can use the gem binary from the command line, or the Gem API inside a ruby process at runtime.

gem binary (in a terminal)

You can get some information abou...

When writing Rails migrations to convert a string column to an integer you'd usually say:

change_column :table_name, :column_name, :integer

However, PostgreSQL will complain:

PG::DatatypeMismatch: ERROR:  column "column_name" cannot...

If you migrate a Rails application from Sprockets to Webpack(er), you can either transpile your CoffeeScript files to JavaScript or integrate a CoffeeScript compil...

In a nutshell: Use git rebase --onto target-branch source-commit

• target-branch means "branch you want to be based on"
• source-commit means "commit before your first feature commit"

Let's say my-feature-branch...

Given there is a user with an attachable avatar:

class User < ApplicationRecord
  has_one_attached :avatar
end

You can copy the avatar from one user to another user with the code below:

user_1 = User.first
user_2 = User.crea...

When you want to copy/move from a shared folder (on Windows guests, for example) and it fails with absurd error messages (lots of text or an error about the target being read-only), you are probably running on Guest Additions that no longer match ...