Postgres Partitions in Elixir Migration

Postgres 11 has a nifty feature around partitions. When a partition exists for a range of values, when you insert into the parent table it’ll get routed to the correct partition. When you update that record’s partition key it will get moved to the correct partition. A default partition feature exists as well so that if you do try to insert something that doesn’t belong in any available partitions, it will be put there instead....

June 3, 2019

Service Objects for Good

Service objects are a handy tool to use in any ruby application, that has complex logic that needs to be extracted out of a controller or model. There are some nice benefits to extracting complex things into a more testable interface. To avoid providing a contrived example, I will use similar code to how uploads on rubyfm are handled. class UploadService attr_reader :user, :logger, :upload def initialize(user, options = {}) @user = user @logger = options[:logger] || NullObject....

April 18, 2018

Error Helpers in C

I’ve been writing a lot of C lately for a game I am working on. I am not a perfect programmer and I would like to catch my bugs before they arise. Thus, I am attempting to learn Rust in my free time. Backtrace Printing a backtrace in C is not incredibly difficult to accomplish. Although the following is fairly primitive, it will aid in your ability to discern what is happening in your program...

January 9, 2017

Ruby Mixins

Mixins are a bit of a touchy spot for me. I am in a love hate relationship when it comes to them. In some cases, they work brilliantly and in other cases they hide complexity. I have a few rules that I try to follow when I am considering using mixins. Does it hide complexity / indirection? Will it benefit the code base to share code? Will it override methods or will methods need to be overriden?...

January 17, 2015

A Ruby Yukata

Let me introduce you to my new library called Yukata. It is a light weight Ruby attribute library that is configurable and extendable. Virtus has been a huge inspiration for this library. I enjoyed the DSL it offered, while allowing me to have a quick way to make data objects. Here is an example on how to utilize Yukata: class Person < Yukata::Base attribute :first_name, String attribute :last_name, String attribute :born_on, DateTime attribute :married, Boolean, default: -> { false } end The #attribute method is straight forward with its meaning....

March 7, 2014

Responding With Errors in Rails

As I work on API projects I find myself having to track down status codes and ensuring a consistent response code for any given error. Keeping these status codes consistent throughout the application starts to become a hassle. A solution that I stumbled upon happened to be something very simple. # /lib/errors/unauthorized_access_error.rb module Errors class UnauthorizedAccessError def status 403 end def message 'unauthorized access' end def to_hash { meta: { code: status, message: message } } end def to_json(*) to_hash....

October 18, 2013

Test Spies

Test spies are a wonderful tool to utilize in the RSpec testing environment. When used in moderation and with care. Test spies require that a called method be stubbed so that it can be checked to see how it was invoked. I have put together a really simple class to demonstrate a test spy. class NotifyUser attr_reader :user def initialize(user) @user = user end def execute(params={}) mailer.notify({ message: params[:message] }) end def mailer SomeMailer....

October 1, 2013

Command Objects

In any Unix based OS the command line reigns supreme. Commmands are predictable, and return zero for success and non-zero for failures. Rules The same principles can be applied to programming with some minor rule alterations. Class name must be in a similar format to VerbNoun (ex. CreateResource). Instance must have an #execute method. It can accept arguments. The only instance method that should be accessed is the #execute method....

July 10, 2013

State Machines

A state machine is an interesting design pattern. The state_machine gem is a great library. It provides a nice structure to declare states and transitions. It also provides nice callback hooks that can be utilized to run specific actions before or after a transition happens. It has hooks into ActiveRecord and saves the model when the transition from one state to another is successful. The gem also works just fine with plain old ruby objects as well....

July 9, 2013

Dumb Data Objects

As a Rails application grows and evolves. Fat models often become rampant in the application. ActiveRecord callbacks are used and models start interacting with other models in ways they should not. Enter the idea of “dumb data objects”. It is nothing more than a simple data structure. It holds state and that is it. Only methods that display data or modify the internal state should be on the model. This is of course very opinionated, but I do believe it has a lot of merit....

July 7, 2013