submission: warn when an anonymous form is created if nameid is unknown (#45758)

tests/backoffice_pages/test_submission.py

@@ -1310,6 +1310,17 @@ def test_backoffice_submission_with_nameid_and_channel(pub, local_user):
     assert formdata.submission_channel == 'mail'
     assert formdata.status == 'wf-new'
 
+    # target user is unknown
+    app = login(get_app(pub))
+    resp = app.get('/backoffice/submission/form-title/?NameID=UNKNOWN_NAMEID')
+    assert resp.location.startswith('http://example.net/backoffice/submission/form-title/')
+    formdata_no = resp.location.split('/')[-2]
+    formdata = formdef.data_class().get(formdata_no)
+    assert not formdata.user_id
+    resp = resp.follow()  # redirect to created draft
+    resp = resp.follow()  # redirect to ?mt=
+    assert 'The target user was not found, this form is anonymous.' in resp.text
+
 
 def test_backoffice_submission_only_one_check(pub, local_user):
     user = create_user(pub)

wcs/backoffice/submission.py

@@ -133,6 +133,11 @@ class FormFillPage(PublicFormFillPage):
                 users = list(get_publisher().user_class.get_users_with_name_identifier(name_id))
                 if users:
                     formdata.user_id = users[0].id
+                else:
+                    get_session().message = (
+                        'warning',
+                        _('The target user was not found, this form is anonymous.'),
+                    )
             if return_url:
                 formdata.submission_context['return_url'] = return_url
             if submission_channel == 'phone' and caller: