ELIXIR ECTO CHANGESET INSTALL
ELIXIR ECTO CHANGESET UPDATE

When I dropped in ember-changeset and ember-changeset-validations into my client app, it instantly clicked with the way I’ve been writing Ember, using DDAU. Instead of 2WBs, changesets allow one way data flow to a model, ensuring that they are always valid, and eliminating a whole class of synchronization headaches. Using changesets in Ember takes the DDAU philosophy used in rendering into the realm of interacting with client side view models. DDAU in Ember.js is built upon the same idea, that data should flow one way. This continues to be a simpler mental model, and just like Elixir (and other functional languages), eliminates a whole class of bugs. Diffing the changes between the virtual and real DOM paved the way for the complete removal of 2WBs - the application simply re-renders whenever there is a change in value. React’s breakthrough was in the use of a virtual DOM, a representation of the actual DOM as a tree-like data structure. 2WBs led to instability and difficult debugging in the form of cascading changes, and React was the first library to attempt to solve this problem. As client side applications matured and became more sophisticated, developers realized that 2WBs were more harmful than useful. 2WBs were the “killer feature” of many JavaScript frameworks when they first debuted. One of the reasons DDAU is so strongly emphasized in Ember 2.x is because it helps us avoid shooting ourselves in the foot with 2 way bindings (2WBs). get ( 'lastName' ) // 'Fallon' Data Down Actions Up, Not 2-Way Bindings set ( 'lastName', 'Fallon' ) let changesetC = changesetA.

set ( 'firstName', 'Jimmy' ) ĬhangesetB. Let changesetA = new Changeset (user, validatorFn ) let changesetB = new Changeset (user, validatorFn ) ĬhangesetA. A colleague I used to work with wrote an excellent blog post on this topic, please check it out if you’re interested in finding out more! Ruby developers would be familiar with this behavior via the method_missing method. These methods are invoked (if present) in Ember.get or t whenever an Ember Object does not define a property. The core concept behind ember-changeset is the definition of unknownProperty and setUnknownProperty. Virtual Properties with unknownProperty and setUnknownProperty Let’s take a look at how ember-changeset is implemented, and we’ll also demonstrate how they align with Ember’s Data Down Actions Up (DDAU) philosophy. It has a simple mental model, and there are no observers or CPs involved - just pure, plain JavaScript functions. The simplest way to incorporate validations is to use ember-changeset-validations, a companion addon. I wrote the addon with compatibility in mind, so it’s easy to wire up with your favorite validation library.

ELIXIR ECTO CHANGESET INSTALL

It turns out that this approach works really well, and I’m happy to announce that you can install it today as an addon with:Įmber install ember-changeset-validations Each form would have a separate changeset, so changes (and validations) would be independent. In my mind, I could see a solution using changesets. This was a poor user experience, since you might edit more than 1 form at a time, but want to separate saves and resets.

ELIXIR ECTO CHANGESET UPDATE

Editing one form would immediately update the model with 2-way bindings. Using ember-form-for and ember-cp-validations, this turned out to be harder than I thought. Each hidden form had separate “toggle”, “save” and “reset” actions. An edit page featured 3 forms, all bound to the same model. The idea for bringing changesets into Ember occurred to me while I was working on a new client app. Ecto is often confused with Rails’ ActiveRecord, but it isn’t an ORM, and shouldn’t be used like one. This ensures that we catch invalid data in the app layer before insertion into the database. Changes are validated and checked against database constraints (such as uniqueness) before casting. One of the core concepts in Ecto is the changeset - an atomic collection of changes.

In Elixir, we use Ecto, a DSL for writing queries and interacting with databases. It turns out whole classes of bugs disappear when embracing immutability and pure functions. That isn’t to say that one is better than the other, but in my experience less unexpected behavior occurs in FP. In fact, I try to use functional approaches wherever possible in JavaScript as well. FP feels more intuitive and less prone to “shoot yourself in the foot” scenarios compared to OOP. I am blown away by how nice it is working with Elixir and functional programming (FP) concepts. The past month or so, I’ve been working on an Elixir and Phoenix API for a client.

Elixir ecto changeset