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Ecto "inheritance" using macros

Oooh them's fighting words. Anyways, this is definitely not true inheritance by any means, but let me explain the problem and then the solution. Ecto is the primary way you connect to the database in Phoenix. However, Ecto differs in many significant ways from ActiveRecord in Rails. You can set up a schema file which lists the relationships between your "models" or "entities", but these schemas do not allow you to directly access the database. They are merely descriptions of how the data is expressed. To access the database, you need to use a data context which uses Ecto. So, from my article comparing Active Record to Ecto ( http://www.skuunk.com/2020/01/comparing-rails-active-record-pattern.html ) defmodule Schema.Article do use Ecto.Schema import Ecto.Changeset alias Schema.Author alias Schema.Comment @permitted_fields [:title, :content] @required_fields [:title, :content] schema "article" do belongs_to(:author, Author) ...

Elixir - destructuring, function overloading and pattern matching

Why am I covering 3 Elixir topics at once? Well, perhaps it is to show you how the three are used together. Individually, any of these 3 are interesting, but combined, they provide you with a means of essentially getting rid of conditionals and spaghetti logic. Consider the following function. def greet_beatle(person) do case person.first_name do "John" -> "Hello John." "Paul" -> "Good day Paul." "George" -> "Georgie boy, how you doing?" "Ringo" -> "What a drummer!" _-> "You are not a Beatle, #{person.first_name}" end end Yeah, it basically works, but there is a big old case statement in there. If you wanted to do something more as well depending on the person, you could easily end up with some spaghetti logic. Let's see how we can simplify this a little. def greet_beatle(%{first_name: first_name}) do case first_name d...

Comparing Rails' Active Record Pattern with Phoenix/Elixir/Ecto

Rails has a very well established Active Record pattern for dealing with the database. You have an Active Record model which maps to the database table, the schema of the model comes directly from the database schema and you place your model specific methods on the Active Record model. This file is also where you set your model relationships (e.g. has_many, has_one, belongs_to). Your instance of the model has all the methods built in. In Ecto/Phoenix it's a little different. First of all, the database schema doesn't automatically map to the "model". In fact we don't really have models (as Elixir is a functional paradigm). What happens in one file in Rails, happens in essentially two (or more). You have a schema file (where you have to list out all the attributes and relationships). Using the schema file, your "instance" is essentially a data structure (with no methods on it). If you want to transform the data on your struct, you would use a context mod...

JavaScript on Rails 2016

Whilst I am primarily a JavaScript programmer, my framework of choice is Ruby on Rails. A lot of JS guys like Node or other frameworks which are JS all the way through, but there's a lot to like about Rails, even in 2016 and it's worth learning another language (Ruby) or two (SQL) in order to get the best environment on which to write your JavaScripts. Before I say what I like about Rails though, I will take you through what I don't like just to balance things out. What I don't like about Rails Asset Pipeline still does not let you use ES6 Modules. Even at this late stage, one still cannot access ES6 Modules in Rails in a "Railsy" manner. You can either bypass the whole Asset Pipeline or else separate out the JS using Webpack or whatever, but in a standard Rails project, the fact that the asset is generated with unique hash in the file name before the extension pretty much nullifies its use for ES6 Modules which need a static location to store the fi...

React: Viewless components

I have been using Facebook's React library for a while now (https://facebook.github.io/react/) and I like it for the most part. The most controversial aspect is the fact that the View is mixed into the Logic using what looks like HTML in the "JavaScript" file using JSX. While it is possible to write React components in plain JavaScript, you must include a render() method. However, it is actually possible to do the following... (in ES6 syntax) render() { return (null); } Now, why would you want to do such a thing? I thought the whole point was to use React to tie together your view and logic layers (and shouldn't you be abstracting out your heavy logic to plain JS classes?). Well, the main reason you might want to do it is because of React's component lifecycle. In my case, I wanted to trigger some JS to run when the component was loaded, and I happen to be using Turbolinks and React-Rails in a Rails project. This JS had ...

Testing React components with Jasmine in Rails with the react-rails gem

So in my latest project, we are using Ruby on Rails and the react-rails gem to implement our React components. While react-rails is fine for the most part (and for simple components), there is a severe limitation in that you cannot use ES6 modules (i.e. using the import and export classes) because of the way asset-pipeline works. Asset-pipeline precompiles all your JS into one mega JS file and therefore doesn't allow you to call individual JavaScript components in separate files (because they don't pushed to the server). This is a severe problem which I hope gets fixed soon, but in the meantime don't hold your breath. There are workarounds using Browserify and/or Webpack, but they are messy (Google them for more info). In any case, react-rails does allow simple React components in Rails apps and it mounts them all in the window/global namespace, so you can use a good 75% of React within a Rails application. So now, we come to testing... Facebook uses a testing f...