Add the action to get Book by a BookId.

lib/decentralised_book_index/metadata.ex

@@ -30,6 +30,7 @@ defmodule DecentralisedBookIndex.Metadata do
 
       define :list_books, action: :read
       define :get_book_by_id, args: [:id], action: :by_id
+      define :get_book_by_bid, args: [:type, :bid], action: :by_bid
       define :get_book_alternative_editions, args: [:book], action: :get_alternative_editions
       define :get_author_books, args: [:author], action: :get_author_books
       define :update_book, action: :update

lib/decentralised_book_index/metadata/book.ex

@@ -69,6 +69,13 @@ defmodule DecentralisedBookIndex.Metadata.Book do
       filter expr(id == ^arg(:id))
     end
 
+    read :by_bid do
+      argument :type, :string, allow_nil?: false
+      argument :bid, :string, allow_nil?: false
+      get? true
+      filter expr(exists(bids, type == ^arg(:type) and bid == ^arg(:bid)))
+    end
+
     read :get_alternative_editions do
       argument :book, :struct, allow_nil?: false
 

test/decentralised_book_index/metadata/book_test.exs

@@ -117,4 +117,26 @@ defmodule DecentralisedBookIndex.Metadata.BookTest do
       assert book3.id in book_ids
     end
   end
+
+  describe "get a book by book id" do
+    test "get by bid" do
+      {:ok, author} = Metadata.create_author("Author", "An description")
+
+      type = "isbn10"
+      bid = "1234567890"
+
+      bids = [
+        %{order: 1, type: type, bid: bid}
+      ]
+
+      author_roles = [
+        %{order: 1, author_id: author.id, role: ""}
+      ]
+
+      {:ok, expected_book} = Metadata.create_book("Book", "An description", bids, author_roles)
+
+      assert {:ok, book} = Metadata.get_book_by_bid(type, bid)
+      assert expected_book.id == book.id
+    end
+  end
 end