use only authenticate for create token

djoser/auth_backends.py

@@ -0,0 +1,29 @@
+from django.contrib.auth import get_user_model
+from django.contrib.auth.backends import ModelBackend
+from djoser.conf import settings
+
+
+UserModel = get_user_model()
+
+
+class LoginFieldBackend(ModelBackend):
+    """Allows to log in by a different value than the default Django
+    USERNAME_FIELD."""
+
+    def authenticate(self, request, username=None, password=None, **kwargs):
+        if username is None:
+            username = kwargs.get(UserModel.USERNAME_FIELD)
+        if username is None or password is None:
+            return
+        get_kwargs = {
+            settings.LOGIN_FIELD: username,
+        }
+        try:
+            user = UserModel._default_manager.get(**get_kwargs)
+        except UserModel.DoesNotExist:
+            # Run the default password hasher once to reduce the timing
+            # difference between an existing and a nonexistent user (#20760).
+            UserModel().set_password(password)
+        else:
+            if user.check_password(password) and self.user_can_authenticate(user):
+                return user

djoser/serializers.py

@@ -117,17 +117,16 @@ def __init__(self, *args, **kwargs):
 
     def validate(self, attrs):
         password = attrs.get("password")
-        params = {settings.LOGIN_FIELD: attrs.get(settings.LOGIN_FIELD)}
+        # https://github.com/sunscrapers/djoser/issues/389
+        # https://github.com/sunscrapers/djoser/issues/429
+        # https://github.com/sunscrapers/djoser/issues/795
+        params = {User.USERNAME_FIELD: attrs.get(settings.LOGIN_FIELD)}
         self.user = authenticate(
             request=self.context.get("request"), **params, password=password
         )
         if not self.user:
-            self.user = User.objects.filter(**params).first()
-            if self.user and not self.user.check_password(password):
-                self.fail("invalid_credentials")
-        if self.user and self.user.is_active:
-            return attrs
-        self.fail("invalid_credentials")
+            self.fail("invalid_credentials")
+        return attrs
 
 
 class UserFunctionsMixin:

docs/source/settings.rst

@@ -32,6 +32,24 @@ Name of a field in User model to be used as login field. This is useful if you
 want to change the login field from ``username`` to ``email`` without providing
 custom User model.
 
+.. versionchanged:: 2.3.0
+
+As the authentication is happening within the Django's authentication backends, you need a
+custom authentication backend that's using ``LOGIN_FIELD`` instead of ``User.USERNAME_FIELD``
+for this setting to work as expected.
+
+If you don't want to roll out your own authentication backend, ``LoginFieldBackend`` has been prepared.
+It works the same as ``ModelBackend``, but it is using ``LOGIN_FIELD`` instead of ``User.USERNAME_FIELD``.
+
+To make your code backward compatible with previous Djoser versions, add this auth backend to your Django settings:
+
+.. code-block:: python
+
+    AUTHENTICATION_BACKENDS = [
+        "djoser.auth_backends.LoginFieldBackend",
+    ]
+
+Please notice that it is not recommended way of authentication and it may be removed in the future Djoser versions.
 **Default**: ``User.USERNAME_FIELD`` where ``User`` is the model set with Django's setting AUTH_USER_MODEL.
 
 .. warning::