feat(chat): add schema to handle room membership

lib/slax/accounts/user.ex

@@ -2,6 +2,9 @@ defmodule Slax.Accounts.User do
   use Ecto.Schema
   import Ecto.Changeset
 
+  alias Slax.Chat.Room
+  alias Slax.Chat.RoomMembership
+
   schema "users" do
     field :email, :string
     field :password, :string, virtual: true, redact: true
@@ -9,6 +12,8 @@ defmodule Slax.Accounts.User do
     field :current_password, :string, virtual: true, redact: true
     field :confirmed_at, :utc_datetime
 
+    many_to_many :rooms, Room, join_through: RoomMembership
+
     timestamps(type: :utc_datetime)
   end
 

lib/slax/chat.ex

@@ -8,6 +8,7 @@ defmodule Slax.Chat do
   alias Slax.Accounts.User
   alias Slax.Chat.Message
   alias Slax.Chat.Room
+  alias Slax.Chat.RoomMembership
   alias Slax.Repo
 
   @pubsub Slax.PubSub
@@ -24,6 +25,10 @@ defmodule Slax.Chat do
     |> Repo.update()
   end
 
+  def join_room!(%Room{} = room, %User{} = user) do
+    Repo.insert!(%RoomMembership{room: room, user: user})
+  end
+
   def change_room(room, attrs \\ %{}) do
     Room.changeset(room, attrs)
   end

lib/slax/chat/room.ex

@@ -1,12 +1,16 @@
 defmodule Slax.Chat.Room do
   use Ecto.Schema
   import Ecto.Changeset
+  alias Slax.Accounts.User
   alias Slax.Chat.Message
+  alias Slax.Chat.RoomMembership
 
   schema "rooms" do
     field :name, :string
     field :topic, :string
 
+    many_to_many :members, User, join_through: RoomMembership
+
     has_many :messages, Message
 
     timestamps(type: :utc_datetime)

lib/slax/chat/room_membership.ex

@@ -0,0 +1,21 @@
+defmodule Slax.Chat.RoomMembership do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  alias Slax.Accounts.User
+  alias Slax.Chat.Room
+
+  schema "room_memberships" do
+    belongs_to :room, Room
+    belongs_to :user, User
+
+    timestamps(type: :utc_datetime)
+  end
+
+  @doc false
+  def changeset(room_membership, attrs) do
+    room_membership
+    |> cast(attrs, [])
+    |> validate_required([])
+  end
+end

priv/repo/migrations/20241117132804_create_room_memberships.exs

@@ -0,0 +1,16 @@
+defmodule Slax.Repo.Migrations.CreateRoomMemberships do
+  use Ecto.Migration
+
+  def change do
+    create table(:room_memberships) do
+      add :user_id, references(:users, on_delete: :delete_all), null: false
+      add :room_id, references(:rooms, on_delete: :delete_all), null: false
+
+      timestamps(type: :utc_datetime)
+    end
+
+    create index(:room_memberships, [:user_id])
+    create index(:room_memberships, [:room_id])
+    create unique_index(:room_memberships, [:user_id, :room_id])
+  end
+end