Birth date is only for participants

apps/registration/models.py

@@ -123,11 +123,6 @@ class ParticipantRegistration(Registration):
         verbose_name=_("team"),
     )
 
-    birth_date = models.DateField(
-        verbose_name=_("birth date"),
-        default=date.today,
-    )
-
     gender = models.CharField(
         max_length=6,
         verbose_name=_("gender"),
@@ -174,6 +169,8 @@ class ParticipantRegistration(Registration):
 
     @property
     def under_18(self):
+        if isinstance(self, CoachRegistration):
+            return False  # In normal case
         important_date = timezone.now().date()
         if self.team and self.team.participation.tournament:
             important_date = self.team.participation.tournament.date_start
@@ -196,6 +193,11 @@ class StudentRegistration(ParticipantRegistration):
     Specific registration for students.
     They have a team, a student class and a school.
     """
+    birth_date = models.DateField(
+        verbose_name=_("birth date"),
+        default=date.today,
+    )
+
     student_class = models.IntegerField(
         choices=[
             (12, _("12th grade")),
@@ -218,7 +220,7 @@ class StudentRegistration(ParticipantRegistration):
 
     responsible_phone = PhoneNumberField(
         verbose_name=_("responsible phone number"),
-        blank=True,
+        default="",
     )
 
     responsible_email = models.EmailField(