Add websocket for subscriptions

lib/gql_preferences/application.ex

@@ -4,6 +4,7 @@ defmodule UserPreferences.Application do
   @moduledoc false
 
   use Application
+  import Supervisor.Spec
   alias ActivityServer
 
   @impl true
@@ -19,7 +20,8 @@ defmodule UserPreferences.Application do
       UserPreferencesWeb.Endpoint,
       # Start a worker by calling: UserPreferences.Worker.start_link(arg)
       # {UserPreferences.Worker, arg}
-      ActivityServer
+      ActivityServer,
+      {Absinthe.Subscription, UserPreferencesWeb.Endpoint}
     ]
 
     # See https://hexdocs.pm/elixir/Supervisor.html

lib/gql_preferences_web/endpoint.ex

@@ -1,5 +1,6 @@
 defmodule UserPreferencesWeb.Endpoint do
   use Phoenix.Endpoint, otp_app: :gql_preferences
+  use Absinthe.Phoenix.Endpoint
 
   # The session will be stored in the cookie and signed,
   # this means its contents can be read but not tampered with.

lib/gql_preferences_web/router.ex

@@ -17,11 +17,11 @@ defmodule UserPreferencesWeb.Router do
   scope "/" do
     pipe_through :api
 
-    forward "/api", Absinthe.Plug,
-      schema: UserPreferencesWeb.Schema
+    forward "/api", Absinthe.Plug, schema: UserPreferencesWeb.Schema
 
     forward "/graphiql", Absinthe.Plug.GraphiQL,
       schema: UserPreferencesWeb.Schema,
+      socket: UserPreferencesWeb.UserSocket,
       interface: :simple
   end
 

lib/gql_preferences_web/user_socket.ex

@@ -0,0 +1,25 @@
+defmodule UserPreferencesWeb.UserSocket do
+  use Phoenix.Socket
+
+  use Absinthe.Phoenix.Socket,
+    schema: UserPreferencesWeb.Schema
+
+  def connect(params, socket) do
+    current_user = current_user(params)
+
+    socket =
+      Absinthe.Phoenix.Socket.put_options(socket,
+        context: %{
+          current_user: current_user
+        }
+      )
+
+    {:ok, socket}
+  end
+
+  defp current_user(%{"user_id" => id}) do
+    MyApp.Repo.get(User, id)
+  end
+
+  def id(_socket), do: nil
+end

mix.exs

@@ -35,6 +35,7 @@ defmodule UserPreferences.MixProject do
     [
       {:absinthe, "~> 1.6"},
       {:absinthe_plug, "~> 1.5"},
+      {:absinthe_phoenix, "~> 2.0"},
       {:absinthe_relay, "~> 1.5"},
       {:phoenix, "~> 1.6.0"},
       {:phoenix_ecto, "~> 4.4"},

mix.lock

@@ -1,5 +1,6 @@
 %{
   "absinthe": {:hex, :absinthe, "1.6.6", "d4b3d87c868264edf47fbf9c152155f31e8d26c370607f5fe92f6e106d190b74", [:mix], [{:dataloader, "~> 1.0.0", [hex: :dataloader, repo: "hexpm", optional: true]}, {:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}, {:nimble_parsec, "~> 0.5 or ~> 1.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}, {:telemetry, "~> 1.0 or ~> 0.4", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "a03e18478b19bdf81ed1eef9b0853edf4496a080c2048ed17993dc945a90bedc"},
+  "absinthe_phoenix": {:hex, :absinthe_phoenix, "2.0.2", "e607b438db900049b9b3760f8ecd0591017a46122fffed7057bf6989020992b5", [:mix], [{:absinthe, "~> 1.5", [hex: :absinthe, repo: "hexpm", optional: false]}, {:absinthe_plug, "~> 1.5", [hex: :absinthe_plug, repo: "hexpm", optional: false]}, {:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:phoenix, "~> 1.5", [hex: :phoenix, repo: "hexpm", optional: false]}, {:phoenix_html, "~> 2.13 or ~> 3.0", [hex: :phoenix_html, repo: "hexpm", optional: true]}, {:phoenix_pubsub, "~> 2.0", [hex: :phoenix_pubsub, repo: "hexpm", optional: false]}], "hexpm", "d36918925c380dc7d2ed7d039c9a3b4182ec36723f7417a68745ade5aab22f8d"},
   "absinthe_plug": {:hex, :absinthe_plug, "1.5.8", "38d230641ba9dca8f72f1fed2dfc8abd53b3907d1996363da32434ab6ee5d6ab", [:mix], [{:absinthe, "~> 1.5", [hex: :absinthe, repo: "hexpm", optional: false]}, {:plug, "~> 1.4", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "bbb04176647b735828861e7b2705465e53e2cf54ccf5a73ddd1ebd855f996e5a"},
   "absinthe_relay": {:hex, :absinthe_relay, "1.5.1", "adf298e77cf83d52bae1d7dc1579146bf9b893fcaa7b556d62e81a8c6f997514", [:mix], [{:absinthe, "~> 1.5.0 or ~> 1.6.0", [hex: :absinthe, repo: "hexpm", optional: false]}, {:ecto, "~> 2.0 or ~> 3.0", [hex: :ecto, repo: "hexpm", optional: true]}], "hexpm", "1fd2a3559f8472c5bac5778c8b87ae5a5d7f89b594eba26b684ce1d0345a910a"},
   "castore": {:hex, :castore, "0.1.12", "b5755d7668668a74c0e3c4c68df91da927e063a5cade17d693eff04e6ab64805", [:mix], [], "hexpm", "981c79528f88ec4ffd627214ad4cdd25052dc56c002996c603011ae37ec1b4b0"},