Set in the data modelling and examples, that broadcast should be done after transaction commit

Author: obieewan

guides/data_modelling/cross_context_boundaries.md

@@ -551,12 +551,19 @@ Head back over to your shopping cart context in `lib/hello/shopping_cart.ex` and
       |> Ecto.Changeset.cast_assoc(:items, with: &CartItem.changeset/2)
 
     Repo.transact(fn ->
-      with {:ok, cart} <- Repo.update(changeset) do
-        Repo.delete_all(from(i in CartItem, where: i.cart_id == ^cart.id and i.quantity == 0))
-        broadcast_cart(scope, {:updated, cart})
+      with {:ok, cart} <- Repo.update(changeset),
+           {_count, _cart_items} = Repo.delete_all(from(i in CartItem, where: i.cart_id == ^cart.id and i.quantity == 0)) do
         {:ok, cart}
       end
     end)
+    |> case do
+      {:ok, cart} ->
+        broadcast_cart(scope, {:updated, cart})
+        {:ok, cart}
+  
+      {:error, reason} ->
+        {:error, reason}
+    end
   end
 ```
 

guides/data_modelling/more_examples.md

@@ -202,7 +202,6 @@ From our requirements alone, we can start to see why a generic `create_order` fu
   alias Hello.Orders.LineItem
   alias Hello.ShoppingCart
 
-
   def complete_order(%Scope{} = scope, %ShoppingCart.Cart{} = cart) do
     true = cart.user_id == scope.user.id
 
@@ -225,10 +224,17 @@ From our requirements alone, we can start to see why a generic `create_order` fu
     Repo.transact(fn ->
       with {:ok, order} <- Repo.insert(order_changeset),
            {:ok, _cart} <- ShoppingCart.prune_cart_items(scope, cart) do
-        broadcast(scope, {:created, order})
         {:ok, order}
       end
     end)
+    |> case do
+      {:ok, order} ->
+        broadcast_order(scope, {:created, order})
+        {:ok, order}
+  
+      {:error, reason} ->
+        {:error, reason}
+    end
   end
 ```