Aske Doerge Doerge

Phoenix 1.4.x to 1.5.0 upgrade instructions

Phoenix 1.5 requires Elixir >= 1.7. Be sure your existing version is up to date by running elixir -v on the command line.

Install the new phx.new project generator

$ mix archive.uninstall phx_new
$ mix archive.install hex phx_new 1.5.0

Renaming table in Ecto migration

I recently wanted to rename a model and its postgres table in a Phoenix app. Renaming the table was simple and documented, but the table also had constraints, sequences, and indexes that needed to be updated in order for the Ecto model to be able to rely on default naming conventions. I couldn't find any examples of what this would look like but was eventually able to figure it out. For anyone else in the same situation, hopefully this example helps.

In the example below, I'm renaming the Permission model to Membership. This model belongs to a User and an Account, so it has foreign key constraints that need to be renamed.

defmodule MyApp.Repo.Migrations.RenamePermissionsToMemberships do
  use Ecto.Migration

The Complete Guide to Nested Forms in Phoenix

I recently spent some time dealing with nested forms in Phoenix. Nested forms are great when you want to create multiple database records in a single transaction and associate them with each other. I am new to Phoenix and really struggled to find any resources that helped me with my specific problem. I decided to document what I learned in the process in hopes of helping others that are new to Elixir and Phoenix.

Here is my attempt at a one stop shop to learn everything you will need to know about nested forms. If you would like to view the GitHub repo you can check it out here.

Thanks to Heartbeat and Jose for excellent blog posts on nested forms. Also shoutout to Josh for showing me some examples at Ruby

This is a list inspired by some of our current or potential lines of work at the World Bank Innovation Labs. The “Innovations in Big Data Analytics” program helps to strengthen the World Bank capabilities to effectively use big data in its operational and strategic work.

We are always looking for great Data Scientists. If you can solve any of these [using open software], you'll be heads down helping us from day one. Email us to [email protected]

(This list is updated frequently).

1. Nightlights from Satellite

We are building an open stack to process nightly data from satellite and query light output from all known villages. Currently we are doing 20 years of nightly data for 600,000 villages in India.

Default

Powerlevel10k

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

	defmodule Mix.Tasks.ConvertToVerifiedRoutes do
	@shortdoc "Fix routes"

	use Mix.Task

	@regex ~r/(Routes\.)(.)_(path\|url)\(.?\)/
	@web_module MyAppWeb

	def run(_) do
	Path.wildcard("lib/*/.*ex")