Elixir has a very flexible feature called Protocols. These can be used for helper utilities modules.
defprotocol Double do
def double(input)
end
defimpl Double, for: Integer do
def double(int) do
int * 2
end
end
defimpl Double, for: List do
def double(list) do
list ++ list
end
end
Hoping I can do more on how this can be used in a phoenix app.
Although it is not super intuitive since it does not belong to the Map module, Elixir has a built in get_in function which is used to retrieve a nested value in nested maps using an array of keys.
movie_map = %{ movie: %{ title: "Deadpool"} }
title = get_in(movie_map, [:movie, :title])
=> nil
# When value is not present, returns nil
description = get_in(movie_map, [:movie, :description])
=> nil
director_name = get_in(movie_map, [:movie, :cast, :director, :first_name])
=> nil
Elixir has a powerful withconstruct that isn’t availabe in ruby. This is an elegant pattern for a language. It can be used to pull out individual values or it can be chained.
Individual value example (yes, a bit contrived):
def divide(values) do
with {:ok, dividend} <- Map.fetch(values, :dividend),
{:ok, divisor} <- Map.fetch(values, :divisor) do
{:ok, dividend / divisor}
end
end
In this article I share how I was able to create a Baby Age Calculator using Phoenix/Elixir LiveView.
If you just want to know how old your child is, jump over to babyweeks.herokuapp.com. If you want to download the source code, goto github.com/monkseal/babyweeks-phx-liveview
As described here and here — “Phoenix LiveView is an exciting new library which enables rich, real-time user experiences with server-rendered HTML. LiveView powered applications are stateful on the server with bidrectional communication via WebSockets, offering a vastly simplified programming model compared to JavaScript alternatives.”
If you don’t want to write Javascript to have a real-time web application, Phoenix LiveView provides an interesting alternative with server-rendered HTML.
Being one to avoid bold pronouments, I won’t commit myself to say that LiveView will deal a death blow to javascript in your app. For one, you may already have a lot Javascript in your app. Maybe some if you even like. However, if you are interested in managing state on the server, LiveView is quite compelling.
After over 12 years of working with Ruby on Rails on multiple different codebases, I’ve some common themes. This is my list of patterns or types of objects you will see in Rails applications.
ActiveRecord provides the scope macro which allows us to define queries related to that model. However, for larger, more complex queries that span multiple models, scopes can often lead to a patchwork of distributed logic. To address this, I prefer to build stand alone a Query object. I usually place this in a separate folder: `app/queries’. The following is an example of query object:
A simple base query object:
module Kenglish
QueryResult = Struct.new(:data, :meta)
class Query
class << self
def result(*args)
new(*args).result
end
end
attr_reader :params, :relation
def initialize(params, relation)
@params = params
@relation = relation
end
def build_result(data, meta)
QueryResult.new(data, meta)
end
end
end
I have worked with a few engineering teams and managers that expressed something like this:
Our current system is so buggy and problematic, if we could just throw the whole thing out and start over we wouldn’t have all these issues!
This sentiment expresses a common human desire for a fresh start, a do-over. Our legal system accommodates this through personal and corporate bankruptcies. For a brick and mortar business like a Salon or a Restaurant, this might take the form of moving locations or wall-to-wall demolition. Why can’t we do with this our software projects?
Driving, walking, doing dishes, I always seem to be listening to something. Most of these are non-tech but here’s what I’ve listened to the most last year: EconTalk One of the first podcasts I ever subscribed to, this year the host, Russ Roberts, has brought on a wide range of guests. Revolutions I found this one on vacation when I was looking for something long to listen to. I started from the beginning and I’m still on the episodes from 2017!
I recently created a gem for managing migrations in Contentful. It works similar to Rails Migrations. For the full docs, view contentful-migrations.rb on github
git log --pretty=oneline master..your-branch | grep -e '[A-Z]\+-[0-9]\+' -o | sort -u
Many of my blog readers have discovered my article on how to add the Jira Issue Number to Git Commit Message and I continue to work with projects where we make use of the Atlassian toolchain, most prominently Jira for issue tracking and Confluence as a Wiki.