Add transformers for AuthorRole.

lib/decentralised_book_index/sync/data_transformers/author_role_transformer.ex

@@ -0,0 +1,20 @@
+defmodule DecentralisedBookIndex.Sync.DataTransformers.AuthorRoleTransformer do
+  def from_json(json_body) do
+    json_body =
+      if Map.has_key?(json_body, "data") do
+        json_body["data"]
+      else
+        json_body
+      end
+
+    attrs =
+      %{
+        id: get_in(json_body, ["id"]),
+        order: get_in(json_body, ["attributes", "order"]),
+        role: get_in(json_body, ["attributes", "role"]),
+        author_id: get_in(json_body, ["attributes", "author_id"])
+      }
+
+    {:ok, attrs}
+  end
+end

lib/decentralised_book_index/sync/data_transformers/author_roles_transformer.ex

@@ -0,0 +1,21 @@
+defmodule DecentralisedBookIndex.Sync.DataTransformers.AuthorRolesTransformer do
+  alias DecentralisedBookIndex.Sync.DataTransformers.AuthorRoleTransformer
+
+  def from_json(json_body) do
+    json_body =
+      if Map.has_key?(json_body, "data") do
+        json_body["data"]
+      else
+        json_body
+      end
+
+    {:ok,
+     Enum.map(
+       json_body,
+       fn record ->
+         {:ok, record} = AuthorRoleTransformer.from_json(record)
+         record
+       end
+     )}
+  end
+end