From 7965494cb32c5105246480297532037f01573f17 Mon Sep 17 00:00:00 2001
From: Valeri Karpov <val@karpov.io>
Date: Thu, 26 Jul 2018 18:17:32 -0400
Subject: [PATCH] fix(connection): throw helpful error when using legacy
 `mongoose.connect()` syntax

Fix #6756
---
 lib/connection.js | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/connection.js b/lib/connection.js
index 9488bbcca53..069b4af543d 100644
--- a/lib/connection.js
+++ b/lib/connection.js
@@ -414,6 +414,13 @@ Connection.prototype.openUri = function(uri, options, callback) {
     options = null;
   }
 
+  if (['string', 'number'].indexOf(typeof options) !== -1) {
+    throw new MongooseError('Mongoose 5.x no longer supports ' +
+      '`mongoose.connect(host, dbname, port)` or ' +
+      '`mongoose.createConnection(host, dbname, port)`. See ' +
+      'http://mongoosejs.com/docs/connections.html for supported connection syntax');
+  }
+
   const Promise = PromiseProvider.get();
   const _this = this;