[member] Check membership of parent club

apps/member/models.py

@@ -4,6 +4,7 @@
 import datetime
 
 from django.conf import settings
+from django.core.exceptions import ValidationError
 from django.db import models
 from django.urls import reverse, reverse_lazy
 from django.utils.translation import gettext_lazy as _
@@ -165,6 +166,12 @@ class Membership(models.Model):
         else:
             return self.date_start.toordinal() <= datetime.datetime.now().toordinal()
 
+    def save(self, *args, **kwargs):
+        if self.club.parent_club is not None:
+            if not Membership.objects.filter(user=self.user, club=self.club.parent_club):
+				raise ValidationError(_('User is not a member of the parent club'))
+        super().save(*args, **kwargs)
+
     class Meta:
         verbose_name = _('membership')
         verbose_name_plural = _('memberships')