From 11fca8dc8e01b557d151af6136a240255b7601e8 Mon Sep 17 00:00:00 2001
From: Jonathan Sundqvist <sundqvist.jonathan@gmail.com>
Date: Sun, 11 Jul 2021 21:58:06 +0200
Subject: [PATCH] Introduce our own ModelBackend to reduce queries

---
 account/auth_backends.py | 26 +++++++++++++++++++++++---
 account/models.py        |  7 +++----
 docs/installation.rst    |  7 +++++++
 3 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/account/auth_backends.py b/account/auth_backends.py
index d3777edb..a1d759d3 100644
--- a/account/auth_backends.py
+++ b/account/auth_backends.py
@@ -6,13 +6,31 @@
 from account.utils import get_user_lookup_kwargs
 
 
-class UsernameAuthenticationBackend(ModelBackend):
+User = get_user_model()
+
+
+class AccountModelBackend(ModelBackend):
+    """
+    This authentication backend ensures that the account is always selected
+    on any query with the user, so we don't issue extra unnecessary queries
+    """
+
+    def get_user(self, user_id):
+        """Get the user and select account at the same time"""
+        user = User._default_manager.filter(pk=user_id).select_related('account').first()
+        if not user:
+            return None
+        return user if self.user_can_authenticate(user) else None
+
+
+class UsernameAuthenticationBackend(AccountModelBackend):
+    """Username authentication"""
 
     def authenticate(self, request, username=None, password=None, **kwargs):
+        """Authenticate the user based on user"""
         if username is None or password is None:
             return None
 
-        User = get_user_model()
         try:
             lookup_kwargs = get_user_lookup_kwargs({
                 "{username}__iexact": username
@@ -25,9 +43,11 @@ def authenticate(self, request, username=None, password=None, **kwargs):
             return user
 
 
-class EmailAuthenticationBackend(ModelBackend):
+class EmailAuthenticationBackend(AccountModelBackend):
+    """Email authentication"""
 
     def authenticate(self, request, username=None, password=None, **kwargs):
+        """Authenticate the user based email"""
         qs = EmailAddress.objects.filter(Q(primary=True) | Q(verified=True))
 
         if username is None or password is None:
diff --git a/account/models.py b/account/models.py
index 7d479a11..01eee91f 100644
--- a/account/models.py
+++ b/account/models.py
@@ -38,10 +38,9 @@ class Account(models.Model):
     def for_request(cls, request):
         user = getattr(request, "user", None)
         if user and user.is_authenticated:
-            try:
-                return Account._default_manager.get(user=user)
-            except Account.DoesNotExist:
-                pass
+            account = user.account
+            if account:
+                return account
         return AnonymousAccount(request)
 
     @classmethod
diff --git a/docs/installation.rst b/docs/installation.rst
index 2f83a991..32ff4afd 100644
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -67,6 +67,13 @@ Optionally include ``account.middleware.ExpiredPasswordMiddleware`` in
         ...
     ]
 
+Set the authentication backends to the following::
+
+    AUTHENTICATION_BACKENDS = [
+        'account.auth_backends.AccountModelBackend',
+        'django.contrib.auth.backends.ModelBackend'
+    ]
+
 Once everything is in place make sure you run ``migrate`` to modify the
 database with the ``account`` app models.