Use username as fallback

lib/chore_tracker/accounts.ex

@@ -376,4 +376,8 @@ defmodule ChoreTracker.Accounts do
       {:error, :user, changeset, _} -> {:error, changeset}
     end
   end
+
+  def display_user(%User{} = user) do
+    user.display_name || user.username
+  end
 end

lib/chore_tracker_web/components/layouts.ex

@@ -1,5 +1,6 @@
 defmodule ChoreTrackerWeb.Layouts do
   use ChoreTrackerWeb, :html
+  alias ChoreTracker.Accounts
 
   embed_templates "layouts/*"
 
@@ -9,7 +10,7 @@ defmodule ChoreTrackerWeb.Layouts do
       <nav class="flex items-center gap-4 px-6 justify-end">
         <%= if @current_user do %>
           <p class="text-sm font-medium mr-2">
-            <%= @current_user.display_name %>
+            <%= Accounts.display_user(@current_user) %>
           </p>
           <.header_link href={~p"/users/settings"}>
             Settings

lib/chore_tracker_web/live/chore_live/form_component.ex

@@ -113,6 +113,6 @@ defmodule ChoreTrackerWeb.ChoreLive.FormComponent do
       |> Enum.map(& &1.data.id)
 
     Accounts.list_users()
-    |> Enum.map(&[key: &1.display_name, value: &1.id, selected: &1.id in existing_ids])
+    |> Enum.map(&[key: Accounts.display_user(&1), value: &1.id, selected: &1.id in existing_ids])
   end
 end

lib/chore_tracker_web/live/chore_live/show.ex

@@ -1,7 +1,9 @@
 defmodule ChoreTrackerWeb.ChoreLive.Show do
+  alias ChoreTracker.Chores.Chore
   use ChoreTrackerWeb, :live_view
 
   alias ChoreTracker.Chores
+  alias ChoreTracker.Accounts
 
   @impl true
   def mount(_params, _session, socket) do

lib/chore_tracker_web/live/chore_live/show.html.heex

@@ -44,7 +44,7 @@
     <% else %>
       <ul>
         <%= for assignee <- @chore.assignees do %>
-          <li><%= assignee.display_name %></li>
+          <li><%= Accounts.display_user(assignee) %></li>
         <% end %>
       </ul>
     <% end %>
@@ -56,7 +56,7 @@
       <p>There are no logs</p>
     <% else %>
       <.table id="chore_logs" rows={@chore.logs}>
-        <:col :let={chore_log} label="User"><%= chore_log.user.display_name %></:col>
+        <:col :let={chore_log} label="User"><%= Accounts.display_user(chore_log.user) %></:col>
         <:col :let={chore_log} label="Execution date">
           <span class="flex gap-3">
             <span>

lib/chore_tracker_web/live/overview_live.ex

@@ -38,7 +38,7 @@ defmodule ChoreTrackerWeb.OverviewLive do
       <:col :let={chore} label="Next assignee">
         <%= case Chores.next_chore_assignee(chore) do
           nil -> "No assignee"
-          %Accounts.User{} = user -> user.display_name
+          %Accounts.User{} = user -> Accounts.display_user(user)
         end %>
       </:col>
       <:action :let={chore}>