Update BookId to add the reference logic.

lib/decentralised_book_index/metadata/book_id.ex

@@ -9,16 +9,25 @@ defmodule DecentralisedBookIndex.Metadata.BookId do
   postgres do
     table "book_ids"
     repo DecentralisedBookIndex.Repo
+
+    references do
+      reference :book, index?: true, on_delete: :delete
+    end
   end
 
   actions do
-    defaults [:read, :update, :destroy]
+    defaults [:read, :destroy]
 
     create :create do
       primary? true
       accept [:type, :bid, :order]
     end
 
+    update :update do
+      primary? true
+      accept [:type, :bid, :order]
+    end
+
     read :by_id do
       argument :id, :uuid, allow_nil?: false
       get? true