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Phoenix 1.4.x to 1.5.0 upgrade instructions

Phoenix 1.5 requires Elixir >= 1.7. Be sure your existing version is up to date by running elixir -v on the command line.

Install the new project generator

$ mix archive.uninstall phx_new
$ mix archive.install hex phx_new 1.5.0

Bump your deps

Update your Phoenix and Phoenix PubSub deps to their latest versions.

Note: The outdated Phoenix.Endpoint.CowboyAdapter for Cowboy 1 is deprecated. Please make sure {:plug_cowboy, "~> 2.1"} is specified in your deps.

  defp deps do
      {:phoenix, "~> 1.5.0"},
      {:phoenix_pubsub, "~> 2.0"},
      {:plug_cowboy, "~> 2.1"},

PubSub 2.0 Changes

Phoenix.PubSub 2.0 provides a simpler, more extensible, and more performant Phoenix.PubSub API. For users of Phoenix.PubSub, the API is the same, but the pubsub server being started by the endpoint has been deprecated in favor of starting the PubSub server yourself. This prevents race conditions on startup and decouples the PubSub system from the endpoint.

First, replace your endpoint's :pubsub config with a new :pubsub_server key in config/config.exs:

config :my_app, MyApp.Endpoint,
  url: [host: "localhost"],
- pubsub: [name: MyApp.PubSub, adapter: Phoenix.PubSub.PG2],
+ pubsub_server: MyApp.PubSub,

Next, update your lib/my_app/application.ex supervision tree to start its own PubSub:

children = [
+ # Start the PubSub system
+ {Phoenix.PubSub, name: MyApp.PubSub},
  # Start the Endpoint (http/https)

Update your layouts

Rendering the child template from layouts is deprecated. Replace:

<%= render(@view_module, @view_template, assigns) %>

With the new @inner_content assign:

<%= @inner_content %>

Update your Tests

Using Phoenix.ConnTest is deprecated, replace usage:

use Phoenix.ConnTest


import Plug.Conn
import Phoenix.ConnTest

Note: for most applications, this will be located in a single place in test/support/conn_case.ex

Add the new Phoenix LiveDashboard (optional)

The new LiveDashboard project provides real-time performance monitoring and debugging tools for Phoenix developers. Follow the steps in the project readme to include it in your existing applications

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epinault commented Oct 12, 2020

I think there is a bit more than that ?

 def live_view do
    quote do
      use Phoenix.LiveView,
        layout: {HelloWeb.LayoutView, "live.html"}


  def live_component do
    quote do
      use Phoenix.LiveComponent

was also added to the _web.ex file?

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There is a difference in how render/3 handles assigns which you should be aware of when migrating.

On Phoenix v1.4 render/3 was only checking if assigns is a map with the is_map/1 guard. This is also true for structs.

On Phoenix v1.5 render/3 is piping assigns into which only works for enumerables, which by default is not implemented for structs. Structs have to specifically implement enumerable protocol.

@epinault, features being added would be upgrading, which is not required when migrating. Though I agree it is helpful to mention here.

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benonymus commented Dec 27, 2020

Hey, I was looking for some more info on how to migrate from 1.4 to 1.5 specifically regarding the inner_content situation, and with the lack of examples, I generated a new phoenix projects, and then ran
mix phx.gen.html Accounts User users name:string age:integer
From the docs, and this still generates the files the "old" way, with render in the templates.

The relevant part in edit .html.eex looks like this

<%= render "form.html", Map.put(assigns, :action, Routes.user_path(@conn, :update, @user)) %>

This on phoenix 1.5.7
Any plans on updating the generators?

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@benonymus, using render is still fine almost everywhere. Render was only deprecated from the layout.

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@josevalim, Oh snap I see it now, it is one warning given on every render, and it is just the app layout, not the templates themselves!


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