From 2eb93140f086d5e1c8a227b78bc2cf59e5bad4c6 Mon Sep 17 00:00:00 2001
From: Valeri Karpov <val@karpov.io>
Date: Fri, 1 Jul 2022 14:33:03 -0400
Subject: [PATCH] fix: keep autoIndex & autoCreate as true by default if read
 preference is primaryPreferred

Fix #11976
Re: #9941
---
 lib/helpers/processConnectionOptions.js | 2 +-
 test/connection.test.js                 | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/helpers/processConnectionOptions.js b/lib/helpers/processConnectionOptions.js
index 214a0096050..a9d862b1030 100644
--- a/lib/helpers/processConnectionOptions.js
+++ b/lib/helpers/processConnectionOptions.js
@@ -9,7 +9,7 @@ function processConnectionOptions(uri, options) {
     ? opts.readPreference
     : getUriReadPreference(uri);
 
-  const resolvedOpts = (readPreference && readPreference !== 'primary')
+  const resolvedOpts = (readPreference && readPreference !== 'primary' && readPreference !== 'primaryPreferred')
     ? resolveOptsConflicts(readPreference, opts)
     : opts;
 
diff --git a/test/connection.test.js b/test/connection.test.js
index c586f589982..332fb8e05af 100644
--- a/test/connection.test.js
+++ b/test/connection.test.js
@@ -1074,6 +1074,13 @@ describe('connections:', function() {
         assert.equal(conn2.get('autoCreate'), false);
       });
 
+      it('keeps autoIndex & autoCreate as true by default if read preference is primaryPreferred (gh-9374)', function() {
+        const conn = new mongoose.createConnection(start.uri, { readPreference: 'primaryPreferred' });
+
+        assert.equal(conn.get('autoIndex'), undefined);
+        assert.equal(conn.get('autoCreate'), undefined);
+      });
+
       it('throws if options try to set autoIndex to true', function() {
         const opts = {
           readPreference: 'secondary',