From 50ea98db82217bbd9a2f37ad57f6f271b2bff7c2 Mon Sep 17 00:00:00 2001
From: zookzook <zookzook@unitybox.de>
Date: Tue, 19 Sep 2023 16:16:30 +0200
Subject: [PATCH] fix: handle read preferences without tags

---
 lib/mongo/url_parser.ex        | 4 ++++
 test/mongo/url_parser_test.exs | 9 +++++++++
 2 files changed, 13 insertions(+)

diff --git a/lib/mongo/url_parser.ex b/lib/mongo/url_parser.ex
index 5fa8050c..736070b1 100644
--- a/lib/mongo/url_parser.ex
+++ b/lib/mongo/url_parser.ex
@@ -236,6 +236,10 @@ defmodule Mongo.UrlParser do
     end
   end
 
+  defp parse_tags([]) do
+    []
+  end
+
   defp parse_tags(tags) do
     tags
     |> String.split(",")
diff --git a/test/mongo/url_parser_test.exs b/test/mongo/url_parser_test.exs
index c65b52b5..09a9c51a 100644
--- a/test/mongo/url_parser_test.exs
+++ b/test/mongo/url_parser_test.exs
@@ -124,6 +124,15 @@ defmodule Mongo.UrlParserTest do
                ]
              ]
 
+      assert UrlParser.parse_url(url: "mongodb://seed1.domain.com:27017,seed2.domain.com:27017/db_name?readPreference=secondary&maxStalenessSeconds=30") == [
+               database: "db_name",
+               read_preference: %{mode: :secondary, max_staleness_ms: 30_000},
+               seeds: [
+                 "seed1.domain.com:27017",
+                 "seed2.domain.com:27017"
+               ]
+             ]
+
       assert UrlParser.parse_url(url: "mongodb://seed1.domain.com:27017,seed2.domain.com:27017/db_name?readPreference=weird&readPreferenceTags=dc:ny,rack:r&maxStalenessSeconds=30") == [
                database: "db_name",
                seeds: [