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Phoenix 1.3.x to 1.4.0 Upgrade Guides

Phoenix 1.4 ships with exciting new features, most notably with HTTP2 support, improved development experience with faster compile times, new error pages, and local SSL certificate generation. Additionally, our channel layer internals receiveced an overhaul, provided better structure and extensibility. We also shipped a new and improved Presence javascript API, as well as Elixir formatter integration for our routing and test DSLs.

This release requires few user-facing changes and should be a fast upgrade for those on Phoenix 1.3.x.

Install the new project generator

The mix archive can now be installed via hex, for a simpler, versioned installation experience.

To grab the new archive, simply run:

$ mix archive.uninstall phx_new
$ mix archive.install hex phx_new 1.4.0

Update Phoenix and Cowboy deps

To get started, simply update your Phoenix dep in mix.exs:

{:phoenix, "~> 1.4.0"}

Next, replace your :cowboy dependency with :plug_cowboy:

{:plug_cowboy, "~> 2.0"}
{:plug, "~> 1.7"}

To upgrade to Cowboy 2 for HTTP2 support, use ~> 2.0 as above. To stay on cowboy 1, pass ~> 1.0.

Finally, remove your explicit :ecto dependency and update your :phoenix_ecto and :ecto_sql dependencies with the following versions:

  {:ecto_sql, "~> 3.0"},
  {:phoenix_ecto, "~> 4.0"}

After running mix deps.get, then be sure to grab the latest npm pacakges with:

$ cd assets
$ npm install

Update your Jason configuration

Phoenix 1.4 uses Jason for json generation in favor of poison. Poison may still be used, but you must add :poison to your deps to continue using it on 1.4. To use Jason instead, :jason to your deps in mix.exs:

  {:jason, "~> 1.0"},

Then add the following configuration in config/config.exs:

# Use Jason for JSON parsing in Phoenix
config :phoenix, :json_library, Jason

Update your UserSocket

Phoenix 1.4 deprecated the transport macro, in favor of providing transport information directly on the socket call in your endpoint. Make the following changes:

# app_web/channels/user_socket.ex
- transport :websocket, Phoenix.Transports.WebSocket
- transport :longpoll, Phoenix.Transports.LongPoll, [check_origin: ...]

# app_web/endpoint.ex
- socket "/socket", MyAppWeb.UserSocket
+ socket "/socket", MyAppWeb.UserSocket, 
+   websocket: true # or list of options
+   longpoll: [check_origin: ...]

Update your Presence javascript

A new, backwards compatible Presence JavaScript API has been introduced to both resolve race conditions as well as simplify the usage. Previously, multiple channel callbacks against "presence_state and "presence_diff" events were required on the client which dispatched to Presence.syncState and Presence.syncDiff functions. Now, the interface has been unified to a single onSync callback and the presence instance tracks its own channel callbacks and state. For example:

import {Socket, Presence} from "phoenix"

let renderUsers(presence){
-  someContainer.innerHTML = Presence.list(presence, (id, user) {
-    `<br/>${escape(}`
-  }.join("")
+  someContainer.innerHTML = presence.list((id, user) {
+    `<br/>${escape(}`   
+  }).join("")

let onJoin = (id, current, newPres) => {
    console.log("user has entered for the first time", newPres)
  } else {
    console.log("user additional presence", newPres)
let onLeave = (id, current, leftPres) => {
  if(current.metas.length === 0){
    console.log("user has left from all devices", leftPres)
  } else {
    console.log("user left from a device", leftPres)

let channel = new"...")
- let presence = {}
- channel.on("presence_state", state => {
-   presence = Presence.syncState(presence, state, onJoin, onLeave)
-   renderUsers(presence)
- })
- channel.on("presence_diff", diff => {
-   presence = Presence.syncDiff(presence, diff, onJoin, onLeave)
-   renderUsers(presence)
- })
+ let presence = new Presence(channel)

+ presence.onJoin(onJoin)
+ presence.onLeave(onLeave)
+ presence.onSync(() => renderUsers(presence))

Optional Updates

The above changes are the only ones necessary to be up and running with Phoenix 1.4. The remaining changes will bring you up to speed with new conventions, but are strictly optional.

Add formatter support

Phoenix 1.4 includes formatter integration for our routing and test DSLs. Create or ammend your .formatter.exs in the root of your project(s) with the following:

  import_deps: [:phoenix],
  inputs: ["*.{ex,exs}", "{config,lib,priv,test}/**/*.{ex,exs}"]

Add a Routes alias and update your router calls

A Routes alias has been added to app_web.ex for view and controller blocks in favor over the previously imported AppWeb.Router.Helpers.

The new Routes alias makes it clearer where page_path/page_url and friends exist and removes compile-time dependencies across your web stack. To use the latest conventions, make the following changes to app_web.ex:

- import AppWeb.Router.Helpers
+ alias AppWeb.Router.Helpers, as: Routes

Next, update any controllers, views, and templates calling your imported helpers or static_path|url, to use the new alias, for example:

- <%= link "show", to: user_path(@conn, :show, @user) %>
+ <%= link "show", to: Routes.user_path(@conn, :show, @user) %>

- <script type="text/javascript" src="<%= static_url(@conn, "/js/app.js") %>"></script>
+ <script type="text/javascript" src="<%= Routes.static_url(@conn, "/js/app.js") %>"></script>

Replace Brunch with webpack

The mix generator in 1.4 now uses webpack for asset generation instead of brunch. The development experience remains the same – javascript goes in assets/js, css goes in assets/css, static assets live in assets/static, so those not interested in JS tooling nuances can continue the same patterns while using webpack. Those in need of optimal js tooling can benefit from webpack's more sophisticated code bunding, with dead code elimination and more.

To proceed:

  • update assets/package.json to replace Brunch with webpack:
   "repository": {},
   "license": "MIT",
   "scripts": {
-    "deploy": "brunch build --production",
-    "watch": "brunch watch --stdin"
+    "deploy": "webpack --mode production",
+    "watch": "webpack --mode development --watch-stdin"
   "dependencies": {
     "phoenix": "file:../deps/phoenix",
     "phoenix_html": "file:../deps/phoenix_html"
   "devDependencies": {
-    "babel-brunch": "6.1.1",
-    "brunch": "2.10.9",
-    "clean-css-brunch": "2.10.0",
-    "uglify-js-brunch": "2.10.0"

+    "@babel/core": "^7.0.0",
+    "@babel/preset-env": "^7.0.0",
+    "babel-loader": "^8.0.0",
+    "copy-webpack-plugin": "^4.5.0",
+    "css-loader": "^0.28.10",
+    "mini-css-extract-plugin": "^0.4.0",
+    "optimize-css-assets-webpack-plugin": "^4.0.0",
+    "uglifyjs-webpack-plugin": "^1.2.4",
+    "webpack": "4.4.0",
+    "webpack-cli": "^2.0.10"
  • delete assets/brunch-config.js
  • create assets/.babelrc with the following contents:
    "presets": [
  • create assets/webpack.config.js with the following contents:
const path = require('path');
const glob = require('glob');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');

module.exports = (env, options) => ({
  optimization: {
    minimizer: [
      new UglifyJsPlugin({ cache: true, parallel: true, sourceMap: false }),
      new OptimizeCSSAssetsPlugin({})
  entry: {
      './js/app.js': ['./js/app.js'].concat(glob.sync('./vendor/**/*.js'))
  output: {
    filename: 'app.js',
    path: path.resolve(__dirname, '../priv/static/js')
  module: {
    rules: [
        test: /\.js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader'
        test: /\.css$/,
        use: [MiniCssExtractPlugin.loader, 'css-loader']
  plugins: [
    new MiniCssExtractPlugin({ filename: '../css/app.css' }),
    new CopyWebpackPlugin([{ from: 'static/', to: '../' }])
  • Update config/dev.exs to use webpack instead of brunch:
-  watchers: [node: ["node_modules/brunch/bin/brunch", "watch", "--stdin",
+  watchers: [
+    node: [
+      "node_modules/webpack/bin/webpack.js",
+      "--mode",
+      "development",
+      "--watch-stdin",
+      cd: Path.expand("../assets", __DIR__)
+    ]

CSS changes

  • The main CSS bundle must now be imported from the app.js file. Add the following line to the top of assets/js/app.js:
import css from '../css/app.css';
  • If you are using the default css, replace assets/css/phoenix.css with the following:

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