From cba04072c7ae524b3f0b61b5eed987c5e5f361b8 Mon Sep 17 00:00:00 2001
From: Cheena Malhotra <13396919+cheenamalhotra@users.noreply.github.com>
Date: Tue, 11 Jul 2023 12:37:45 -0700
Subject: [PATCH] Add null checks for connection properties (#2137)

---
 .../Connection/ConnectionService.cs           | 39 ++++++++++++++-----
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/src/Microsoft.SqlTools.ServiceLayer/Connection/ConnectionService.cs b/src/Microsoft.SqlTools.ServiceLayer/Connection/ConnectionService.cs
index f7f5d058..40360d4e 100644
--- a/src/Microsoft.SqlTools.ServiceLayer/Connection/ConnectionService.cs
+++ b/src/Microsoft.SqlTools.ServiceLayer/Connection/ConnectionService.cs
@@ -1410,31 +1410,50 @@ namespace Microsoft.SqlTools.ServiceLayer.Connection
                         connectionBuilder.IntegratedSecurity = true;
                         break;
                     case SqlLogin:
-                        connectionBuilder.UserID = connectionDetails.UserName;
-                        connectionBuilder.Password = string.IsNullOrEmpty(connectionDetails.Password)
+                        // Don't erase username from connection string.
+                        if (string.IsNullOrEmpty(connectionBuilder.UserID))
+                        {
+                            connectionBuilder.UserID = connectionDetails.UserName;
+                        }
+                        // Don't erase password from connection string.
+                        if (string.IsNullOrEmpty(connectionBuilder.Password))
+                        {
+                            connectionBuilder.Password = string.IsNullOrEmpty(connectionDetails.Password)
                             ? string.Empty // Support empty password for accounts without password
                             : connectionDetails.Password;
+                        }
                         connectionBuilder.Authentication = SqlAuthenticationMethod.SqlPassword;
                         break;
                     case AzureMFA:
                         if (Instance.EnableSqlAuthenticationProvider)
                         {
-                            connectionBuilder.UserID = connectionDetails.UserName;
+                            if (string.IsNullOrEmpty(connectionBuilder.UserID))
+                            {
+                                connectionBuilder.UserID = connectionDetails.UserName;
+                            }
                             connectionDetails.AuthenticationType = ActiveDirectoryInteractive;
                             connectionBuilder.Authentication = SqlAuthenticationMethod.ActiveDirectoryInteractive;
                         }
-                        else
-                        {
-                            connectionBuilder.UserID = "";
-                        }
                         break;
                     case ActiveDirectoryInteractive:
-                        connectionBuilder.UserID = connectionDetails.UserName;
+                        // Don't erase username from connection string.
+                        if (string.IsNullOrEmpty(connectionBuilder.UserID))
+                        {
+                            connectionBuilder.UserID = connectionDetails.UserName;
+                        }
                         connectionBuilder.Authentication = SqlAuthenticationMethod.ActiveDirectoryInteractive;
                         break;
                     case ActiveDirectoryPassword:
-                        connectionBuilder.UserID = connectionDetails.UserName;
-                        connectionBuilder.Password = connectionDetails.Password;
+                        // Don't erase username from connection string.
+                        if (string.IsNullOrEmpty(connectionBuilder.UserID))
+                        {
+                            connectionBuilder.UserID = connectionDetails.UserName;
+                        }
+                        // Don't erase password from connection string.
+                        if (string.IsNullOrEmpty(connectionBuilder.Password))
+                        {
+                            connectionBuilder.Password = connectionDetails.Password;
+                        }
                         connectionBuilder.Authentication = SqlAuthenticationMethod.ActiveDirectoryPassword;
                         break;
                     default: