🌐(backend) user language from request Content-Language

We want to adapt the email language depend the website
choosen language. We get the website language
from the request Content-Language header.
We adapt the serializer to set the user language
from the request Content-Language header.
Thanks to that our email will be in the right language.

src/backend/core/api/serializers.py

@@ -262,6 +262,7 @@ class InvitationSerializer(serializers.ModelSerializer):
                 "Only owners of a document can invite other users as owners."
             )
 
+        user.language = request.headers.get("Content-Language", "en")
         attrs["document_id"] = document_id
         attrs["issuer"] = user
         return attrs

src/backend/core/tests/test_api_document_invitations.py

@@ -4,6 +4,8 @@ Unit tests for the Invitation model
 import random
 import time
 
+from django.core import mail
+
 import pytest
 from rest_framework import status
 from rest_framework.test import APIClient
@@ -113,6 +115,81 @@ def test_api_document_invitations__create__privileged_members(
         assert models.Invitation.objects.exists() is False
 
 
+def test_api_document_invitations__create__email_from_content_language():
+    """
+    The email generated is from the language set in the Content-Language header
+    """
+    user = factories.UserFactory()
+    document = factories.DocumentFactory()
+    factories.UserDocumentAccessFactory(document=document, user=user, role="owner")
+
+    invitation_values = {
+        "email": "guest@example.com",
+        "role": "reader",
+    }
+
+    assert len(mail.outbox) == 0
+
+    client = APIClient()
+    client.force_login(user)
+    response = client.post(
+        f"/api/v1.0/documents/{document.id}/invitations/",
+        invitation_values,
+        format="json",
+        headers={"Content-Language": "fr-fr"},
+    )
+
+    assert response.status_code == status.HTTP_201_CREATED
+    assert response.json()["email"] == "guest@example.com"
+    assert models.Invitation.objects.count() == 1
+    assert len(mail.outbox) == 1
+
+    email = mail.outbox[0]
+
+    assert email.to == ["guest@example.com"]
+
+    email_content = " ".join(email.body.split())
+    assert "Invitation à rejoindre Docs !" in email_content
+
+
+def test_api_document_invitations__create__email_from_content_language_not_supported():
+    """
+    If the language from the Content-Language is not supported
+    it will display the default language, English.
+    """
+    user = factories.UserFactory()
+    document = factories.DocumentFactory()
+    factories.UserDocumentAccessFactory(document=document, user=user, role="owner")
+
+    invitation_values = {
+        "email": "guest@example.com",
+        "role": "reader",
+    }
+
+    assert len(mail.outbox) == 0
+
+    client = APIClient()
+    client.force_login(user)
+    response = client.post(
+        f"/api/v1.0/documents/{document.id}/invitations/",
+        invitation_values,
+        format="json",
+        headers={"Content-Language": "not-supported"},
+    )
+
+    assert response.status_code == status.HTTP_201_CREATED
+    assert response.json()["email"] == "guest@example.com"
+    assert models.Invitation.objects.count() == 1
+    assert len(mail.outbox) == 1
+
+    email = mail.outbox[0]
+
+    assert email.to == ["guest@example.com"]
+
+    email_content = " ".join(email.body.split())
+    assert "Invitation to join Docs!" in email_content
+
+
 def test_api_document_invitations__create__issuer_and_document_override():
     """It should not be possible to set the "document" and "issuer" fields."""
     user = factories.UserFactory()

src/backend/core/tests/test_models_invitations.py

@@ -177,7 +177,10 @@ def test_models_document_invitations_email():
     assert len(mail.outbox) == 0
 
     factories.UserDocumentAccessFactory(document=document)
-    invitation = factories.InvitationFactory(document=document, email="john@people.com")
+    issuer = factories.UserFactory(language="en-us")
+    invitation = factories.InvitationFactory(
+        document=document, email="john@people.com", issuer=issuer
+    )
 
     # pylint: disable-next=no-member
     assert len(mail.outbox) == 1
@@ -193,6 +196,33 @@ def test_models_document_invitations_email():
     assert "[//example.com]" in email_content
 
 
+def test_models_document_invitations_email_language_fr():
+    """Check email invitation during invitation creation."""
+    member_access = factories.UserDocumentAccessFactory(role="reader")
+    document = member_access.document
+
+    # pylint: disable-next=no-member
+    assert len(mail.outbox) == 0
+
+    factories.UserDocumentAccessFactory(document=document)
+    issuer = factories.UserFactory(language="fr-fr")
+    invitation = factories.InvitationFactory(
+        document=document, email="john@people.com", issuer=issuer
+    )
+
+    # pylint: disable-next=no-member
+    assert len(mail.outbox) == 1
+
+    # pylint: disable-next=no-member
+    email = mail.outbox[0]
+
+    assert email.to == [invitation.email]
+
+    email_content = " ".join(email.body.split())
+    assert "Invitation à rejoindre Docs !" in email_content
+    assert "[//example.com]" in email_content
+
+
 @mock.patch(
     "django.core.mail.send_mail",
     side_effect=smtplib.SMTPException("Error SMTPException"),