Phoenix And Elm: a real use case

This is a Phoenix 1.3 port over of the Phoenix 1.2/Elm Address Book application, created by Ricardo García Vega over a series of posts over at his blog (original app codebase).

See the original branch for the as-close-to-the-original-as-I-could-get-it version of the codebase. Other branches will likely have personal tweaks to the codebase in it.

Installation

Repository

git clone git@github.com:paulfioravanti/phoenix-and-elm.git
cd phoenix-and-elm
mix do deps.get, ecto.create, ecto.migrate, run priv/repo/seeds.exs

Dependencies

Global

npm install --global elm

npm

To install npm dependencies in package.json:

cd assets
npm install

Elm

To install Elm dependencies in elm-package.json:

cd elm
elm-package install

Run code

From the project root directory:

mix phx.server

Open http://localhost:4000 in a browser.

Changes from the original application

• The introduction of Contexts into Phoenix 1.3 required some re-structuring of the application to get it working as expected. I made the decision to put Contact behind an AddressBook context.
• I used Create Elm App to generate the Elm app under the assets directory, so its structure is slightly different to what is in the original.

Notes

Using Create Elm App

If you want to use Create Elm App to have it generate an Elm app in your Phoenix 1.3 project's assets/ directory, you can follow these steps:

npm install create-elm-app --global
cd assets
create-elm-app elm

Code Branches

REST version

The rest branch of this repository (which also the base branch) contains code covering the first five sections of the tutorial. In other words, up to and including Implementing Elm routing, so the communication between back and front ends is done with REST requests via controllers.

Websockets version

The websockets branch of this repository contains code covering all sections of the tutorial. In other words, up to and including Phoenix and Elm WebSockets support, so the communication between back and front ends is done with Websockets requests via channels.

GraphQL version

The graphql branch of this repository used the REST version of the app as a base, but added GraphQL. So the communication between back and front ends is done with GraphQL requests via resolvers.

REST version (refactored)

The rest-refactor branch of this repository contains the same contents as the rest branch, but was refactored to reduce coupling between parent and child modules based on information gleaned about the project using elm-module-graph.

Code from the rest-refactor branch is not currently deployed.

Deployment Notes

Heroku was originally used to deploy each branch to it's own app. The git remotes look like this:

$ git remote -v
heroku-graphql  https://git.heroku.com/phoenix-and-elm-graphql.git (fetch)
heroku-graphql  https://git.heroku.com/phoenix-and-elm-graphql.git (push)
heroku-rest     https://git.heroku.com/phoenix-and-elm-rest.git (fetch)
heroku-rest     https://git.heroku.com/phoenix-and-elm-rest.git (push)
heroku-websockets https://git.heroku.com/phoenix-and-elm-websockets.git (fetch)
heroku-websockets https://git.heroku.com/phoenix-and-elm-websockets.git (push)
origin  git@github.com:paulfioravanti/phoenix-and-elm.git (fetch)
origin  git@github.com:paulfioravanti/phoenix-and-elm.git (push)

So, deploying each version of the app out to Heroku meant deploying its branch out as the master branch:

git push heroku-rest rest:master
git push heroku-websockets websockets:master
git push heroku-graphql graphql:master

Blog Posts

I wrote a couple of blog posts that use this application as an illustrative example:

• Migrating a Phoenix and Elm app from REST to GraphQL: This blog post covers migrating the application API from using REST, to using GraphQL, and shows the steps needed to get the application from the code base in the rest branch, to the codebase in the graphql branch.
• Graph-driven Refactoring in Elm: This blog post covers decoupling parent and child modules and refactoring Elm applications, and shows the steps needed to get the application from the code base in the rest branch, to the codebase in the rest-refactor branch.

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