Allow teachers to add any normal links to the course menu

Normal links do not transmit personal data (like LTI launch does),
so we need a balance between user experience and overzealous
security and data privacy.

Fixes #563

external_services/models.py

@@ -13,8 +13,7 @@
 
 
 def validate_no_domain(value):
-    if value and '://' in value:
-        raise ValidationError(_('URL_CANNOT_CONTAIN_SCHEME_OR_DOMAIN'))
+    pass
 
 
 class LinkService(ModelWithInheritance):
@@ -250,7 +249,7 @@ class MenuItem(UrlMixin, models.Model):
         max_length=256,
         blank=True,
         null=True,
-        help_text=_('MENU_ITEM_MENU_URL_HELPTEXT'""),
+        help_text=_('MENU_ITEM_MENU_URL_HELPTEXT'),
         validators=[validate_no_domain],
     )
     menu_group_label = models.CharField(

locale/en/LC_MESSAGES/django.po

@@ -4791,10 +4791,6 @@ msgstr "This is a draft. Remember to submit your answer for grading!"
 msgid "LTI_SERVICE_COURSE_ENROLLMENT_REQUIRED_FOR_ACCESS"
 msgstr "Course enrolment required for accessing the LTI service."
 
-#: external_services/models.py
-msgid "URL_CANNOT_CONTAIN_SCHEME_OR_DOMAIN"
-msgstr "The URL cannot contain scheme or domain part."
-
 #: external_services/models.py
 msgid "DESTINATION_INTERNAL_PRIVACY_NOTICE"
 msgstr "The destination is hosted internally. Link to internal privacy notice."
@@ -4978,13 +4974,13 @@ msgstr "URL"
 #: external_services/models.py
 msgid "MENU_ITEM_MENU_URL_HELPTEXT"
 msgstr ""
-"An URL that is a) relative to the service URL or b) this course if no "
-"service is selected.<br>\n"
-"Case a: An URL starting with '/' overwrites path in service URL and extends "
+"A URL that is a) relative to the service URL or b) this course if no service "
+"is selected or c) a link to some external website.<br>\n"
+"Case a: A URL starting with '/' overwrites path in service URL and extends "
 "it otherwise.<br>\n"
-"Case b: An URL starting with '/' is absolute within this service and "
-"relative to the course path otherwise.<br>\n"
-"Note that URL entered here can not include scheme or domain."
+"Case b: A URL starting with '/' is absolute within this service and relative "
+"to the course path otherwise.<br>\n"
+"Case c: A link, for example https://google.com"
 
 #: external_services/models.py
 msgid "LABEL_MENU_GROUP_LABEL"

locale/fi/LC_MESSAGES/django.po

@@ -4805,10 +4805,6 @@ msgstr "Tämä on luonnos. Muista lähettää vastauksesi arvosteltavaksi!"
 msgid "LTI_SERVICE_COURSE_ENROLLMENT_REQUIRED_FOR_ACCESS"
 msgstr "Kurssille ilmoittautuminen vaaditaan LTI-palveluun pääsemiseksi."
 
-#: external_services/models.py
-msgid "URL_CANNOT_CONTAIN_SCHEME_OR_DOMAIN"
-msgstr "Url ei voi sisältää skeema- tai verkkotunnusosaa."
-
 #: external_services/models.py
 msgid "DESTINATION_INTERNAL_PRIVACY_NOTICE"
 msgstr ""
@@ -4998,12 +4994,12 @@ msgstr "URL"
 msgid "MENU_ITEM_MENU_URL_HELPTEXT"
 msgstr ""
 "URL joka on a) suhteellinen palvelun URL:ään tai b) tähän kurssiin, mikäli "
-"palvelua ei ole valittu.<br>\n"
+"palvelua ei ole valittu tai c) linkki ulkoiselle sivustolle.<br>\n"
 "Tilanne a: URL, joka alkaa /-merkillä ylikirjoittaa palvelun koko polun, "
 "muutoin jatkaa sitä.<br>\n"
 "Tilanne b: URL, joka alkaa /-merkillä on absoluuttinen tämän palvelun "
 "suhteen, muutoin on suhteellinen kurssin polkuun.<br>\n"
-"Huomaa ettei tämä URL voi sisältää skeemaa tai verkkotunnusta."
+"Tilanne c: Linkki, esimerkiksi https://google.com"
 
 #: external_services/models.py
 msgid "LABEL_MENU_GROUP_LABEL"