Update Author to sync only a new non-local data.

lib/decentralised_book_index/metadata.ex

@@ -98,6 +98,7 @@ defmodule DecentralisedBookIndex.Metadata do
       define :search_author, action: :search, args: [:name]
       define :update_author, action: :update
       define :assign_author_avatar_image, args: [:avatar_url], action: :assign_avatar_image
+      define :assign_author_dbi_server, args: [:dbi_server_id], action: :assign_dbi_server_id
       define :destroy_author, action: :destroy
     end
 

lib/decentralised_book_index/metadata/author.ex

@@ -195,6 +195,10 @@ defmodule DecentralisedBookIndex.Metadata.Author do
     update :assign_avatar_image do
       accept [:avatar_url]
     end
+
+    update :assign_dbi_server_id do
+      accept [:dbi_server_id]
+    end
   end
 
   policies do

lib/decentralised_book_index/sync/sync/author_sync.ex

@@ -8,15 +8,17 @@ defmodule DecentralisedBookIndex.Sync.AuthorSync do
 
     case Metadata.get_author_by_id(attrs.id) do
       {:ok, author} ->
-        attrs =
+        if not is_local(author) and is_new(attrs, author) do
-          attrs
+          attrs =
-          |> Map.delete(:id)
+            attrs
-          |> update_registry(registry_info)
+            |> Map.delete(:id)
-          |> Map.put(:dbi_server_id, server_id)
+            |> update_registry(registry_info)
+            |> Map.put_new(:dbi_server_id, server_id)
 
-        author
+          author
-        |> Ash.Changeset.for_update(:sync, attrs)
+          |> Ash.Changeset.for_update(:sync, attrs)
-        |> Ash.update!(authorize?: false)
+          |> Ash.update!(authorize?: false)
+        end
 
         :ok
 
@@ -24,7 +26,7 @@ defmodule DecentralisedBookIndex.Sync.AuthorSync do
         attrs =
           attrs
           |> update_registry(registry_info)
-          |> Map.put(:dbi_server_id, server_id)
+          |> Map.put_new(:dbi_server_id, server_id)
 
         Author
         |> Ash.Changeset.for_create(:sync_create, attrs)
@@ -58,4 +60,17 @@ defmodule DecentralisedBookIndex.Sync.AuthorSync do
         |> Map.delete(:author_alias_registry_id)
     end
   end
+
+  defp is_local(author) do
+    is_nil(author.dbi_server_id)
+  end
+
+  defp is_new(new_author, author) do
+    with {:ok, datetime, _offset} <- DateTime.from_iso8601(new_author[:updated_at]) do
+      DateTime.after?(datetime, author.updated_at)
+    else
+      {:error, reason} ->
+        false
+    end
+  end
 end

test/decentralised_book_index/sync/sync/author_sync_test.exs

@@ -90,5 +90,51 @@ defmodule DecentralisedBookIndex.Sync.DataTransformers.AuthorSyncTest do
 
       assert author = saved_author
     end
+
+    test "the local existing author wouldn't updated", %{user: user} do
+      server = generate(dbi_server(url: @test_server_endpoint))
+
+      {:ok, author} = Metadata.create_author("Author", "An description", nil, nil, actor: user)
+
+      author_attrs = %{
+        id: author.id,
+        name: "Author",
+        description: "Something2",
+        avatar_url: "/images/avatar.png",
+        author_alias_registry_id: nil,
+        inserted_at: "2025-03-21T09:20:48.791539Z",
+        updated_at: "2025-03-21T09:20:48.791539Z"
+      }
+
+      assert :ok = AuthorSync.create_update(author_attrs, server.id)
+      assert {:ok, saved_author} = Metadata.get_author_by_id(author.id)
+
+      assert get_submap(saved_author, author_attrs) != author_attrs
+      assert saved_author.name == "Author"
+      assert saved_author.dbi_server_id == nil
+    end
+
+    test "old author wouldn't be sync", %{user: user} do
+      server = generate(dbi_server(url: @test_server_endpoint))
+
+      {:ok, author} = Metadata.create_author("Author", "An description", nil, nil, actor: user)
+      {:ok, author} = Metadata.assign_author_dbi_server(author, server.id, actor: user)
+
+      author_attrs = %{
+        id: author.id,
+        name: "Author",
+        description: "Something2",
+        avatar_url: "/images/avatar.png",
+        author_alias_registry_id: nil,
+        inserted_at: "2025-03-21T09:20:48.791539Z",
+        updated_at: "2025-03-21T09:20:48.791539Z"
+      }
+
+      assert :ok = AuthorSync.create_update(author_attrs, server.id)
+      assert {:ok, saved_author} = Metadata.get_author_by_id(author.id)
+
+      assert get_submap(saved_author, author_attrs) != author_attrs
+      assert saved_author.name == "Author"
+    end
   end
 end