🐛(domains) fix attemps to send invitations to existing users

Users can only search other users inside their own organization.
This leads to a bug where we try to invite an email already linked to an user

CHANGELOG.md

@@ -14,7 +14,11 @@ and this project adheres to
 - ✨(front) add show invitations mails domains access #1040
 - ✨(invitations) can delete domain invitations
 
-## Changed
+### Fixed
+
+- 🐛(domains) fix attemps to send invitations to existing users #953
+
+### Changed
 
 - 🏗️(core) migrate from pip to uv
 - ✨(front) add show invitations mails domains access #1040

src/backend/core/models.py

@@ -36,6 +36,8 @@ from core.plugins.registry import registry as plugin_hooks_registry
 from core.utils.webhooks import webhooks_synchronizer
 from core.validators import get_field_validators_from_setting
 
+from mailbox_manager.exceptions import EmailAlreadyKnownException
+
 logger = getLogger(__name__)
 
 current_dir = os.path.dirname(os.path.abspath(__file__))
@@ -997,9 +999,7 @@ class BaseInvitation(BaseModel):
 
         # Check if a user already exists for the provided email
         if User.objects.filter(email=self.email).exists():
-            raise exceptions.ValidationError(
-                {"email": _("This email is already associated to a registered user.")}
-            )
+            raise EmailAlreadyKnownException
 
     @property
     def is_expired(self):

src/backend/core/tests/test_api_team_invitations.py

@@ -171,10 +171,11 @@ def test_api_team_invitations__create__cannot_invite_existing_users():
         format="json",
     )
 
-    assert response.status_code == status.HTTP_400_BAD_REQUEST
-    assert response.json()["email"] == [
-        "This email is already associated to a registered user."
-    ]
+    assert response.status_code == status.HTTP_201_CREATED
+    assert (
+        response.json()["detail"]
+        == "Email already known. Invitation not sent but access created instead."
+    )
 
 
 def test_api_team_invitations__list__anonymous_user():

src/backend/mailbox_manager/api/client/viewsets.py

@@ -13,6 +13,7 @@ from core.api.client.serializers import UserSerializer
 from mailbox_manager import enums, models
 from mailbox_manager.api import permissions
 from mailbox_manager.api.client import serializers
+from mailbox_manager.exceptions import EmailAlreadyKnownException
 from mailbox_manager.utils.dimail import DimailAPIClient
 
 
@@ -363,6 +364,7 @@ class MailDomainInvitationViewset(
         - issuer : User, automatically added from user making query, if allowed
         - domain : Domain, automatically added from requested URI
         Return a newly created invitation
+        or an access if email is already linked to an existing user
 
     PUT / PATCH : Not permitted. Instead of updating your invitation,
         delete and create a new one.
@@ -410,6 +412,34 @@ class MailDomainInvitationViewset(
 
         return queryset
 
+    def perform_create(self, serializer):
+        """Lookup for existing user before inviting."""
+        if email := serializer.validated_data["email"]:
+            existing_user = models.User.objects.filter(email=email)
+            if existing_user.exists():
+                return models.MailDomainAccess.objects.create(
+                    user=existing_user[0],
+                    domain=serializer.validated_data["domain"],
+                    role=serializer.validated_data["role"],
+                )
+
+        return super().perform_create(serializer)
+
+
+    def create(self, request, *args, **kwargs):
+        """Attempt to create invitation. If user is already registered,
+        they don't need an invitation but an access, which we create here."""
+        try:
+            return super().create(request, *args, **kwargs)
+        except EmailAlreadyKnownException as exc:
+            user = models.User.objects.get(email=email)
+
+            models.MailDomainAccess.objects.create(
+                user=user,
+                domain=models.MailDomain.objects.get(slug=kwargs["domain_slug"]),
+                role=request.data["role"],
+            )
+            raise exc
 
 class AliasViewSet(
     mixins.CreateModelMixin,

src/backend/mailbox_manager/exceptions.py

@@ -0,0 +1,18 @@
+"""
+Custom exceptions for mailbox manager app
+"""
+
+from django.utils.translation import gettext_lazy as _
+
+from rest_framework import status
+from rest_framework.exceptions import APIException
+
+
+class EmailAlreadyKnownException(APIException):
+    """Exception raised when trying to create a user with an already existing email address."""
+
+    status_code = status.HTTP_201_CREATED
+    default_detail = _(
+        "Email already known. Invitation not sent but access created instead."
+    )
+    default_code = "email already known"

src/backend/mailbox_manager/tests/api/invitations/test_api_domain_invitations_create.py

@@ -11,7 +11,7 @@ from rest_framework.test import APIClient
 
 from core import factories as core_factories
 
-from mailbox_manager import enums, factories
+from mailbox_manager import enums, factories, models
 from mailbox_manager.api.client import serializers
 
 pytestmark = pytest.mark.django_db
@@ -141,9 +141,10 @@ def test_api_domain_invitations__should_not_create_duplicate_invitations():
     assert response.json()["__all__"] == [
         "Mail domain invitation with this Email address and Domain already exists."
     ]
+    assert models.MailDomainInvitation.objects.count() == 1  # and specifically, not 2
 
 
-def test_api_domain_invitations__should_not_invite_when_user_already_exists():
+def test_api_domain_invitations__should_create_access_when_user_already_exists():
     """Already existing users should not be invited but given access directly."""
     existing_user = core_factories.UserFactory()
 
@@ -152,15 +153,19 @@ def test_api_domain_invitations__should_not_invite_when_user_already_exists():
 
     client = APIClient()
     client.force_login(access.user)
-    invitation_values = serializers.MailDomainInvitationSerializer(
-        factories.MailDomainInvitationFactory.build(email=existing_user.email)
-    ).data
     response = client.post(
         f"/api/v1.0/mail-domains/{access.domain.slug}/invitations/",
-        invitation_values,
+        {
+            "email": existing_user.email,
+            "role": "owner",
+        },
         format="json",
     )
-    assert response.status_code == status.HTTP_400_BAD_REQUEST
-    assert response.json()["email"] == [
-        "This email is already associated to a registered user."
-    ]
+    assert response.status_code == status.HTTP_201_CREATED
+    assert (
+        response.json()["detail"]
+        == "Email already known. Invitation not sent but access created instead."
+    )
+
+    assert not models.MailDomainInvitation.objects.exists()
+    assert models.MailDomainAccess.objects.filter(user=existing_user).exists()