feat: add context methods to mutate rooms

Also, improve user input validation.

lib/slax/chat.ex

@@ -8,6 +8,18 @@ defmodule Slax.Chat do
   alias Slax.Chat.Room
   alias Slax.Repo
 
+  def create_room(attrs) do
+    %Room{}
+    |> Room.changeset(attrs)
+    |> Repo.insert()
+  end
+
+  def update_room(%Room{} = room, attrs) do
+    room
+    |> Room.changeset(attrs)
+    |> Repo.update()
+  end
+
   def get_first_room! do
     query = from(r in Room, limit: 1, order_by: [asc: :name])
     Repo.one!(query)

lib/slax/chat/room.ex

@@ -13,6 +13,11 @@ defmodule Slax.Chat.Room do
   def changeset(room, attrs) do
     room
     |> cast(attrs, [:name, :topic])
-    |> validate_required([:name, :topic])
+    |> validate_required([:name])
+    |> validate_length(:name, max: 80)
+    |> validate_format(:name, ~r/\A[a-z0-9-]+\z/,
+      message: "can only contain lowercase letters, numbers, and dashes"
+    )
+    |> validate_length(:topic, max: 200)
   end
 end