add validation

leftists/models.py

@@ -1,3 +1,4 @@
+from django.core.exceptions import ValidationError
 from django.db import models
 from django.utils.translation import gettext_lazy as _
 from xenua.django.models import RandomSlugPKMixin
@@ -18,12 +19,19 @@ class Domain(models.Model):
         return cls.objects.get(fqdn__iexact=r.get_host())
 
 
+def validate_location(loc):
+    if "/" in loc:
+        raise ValidationError(
+            _('location must not contain a slash')
+        )
+
+
 class ShortLink(RandomSlugPKMixin, models.Model):
     class Meta:
         unique_together = ('domain', 'location')
 
     domain = models.ForeignKey(Domain, related_name='links', on_delete=models.CASCADE)
-    location = models.CharField(_("short link"), max_length=100)
+    location = models.CharField(_("short link"), max_length=100, validators=[validate_location])
     to = models.URLField(_("redirect to"), max_length=2500)
     click_count = models.IntegerField(default=0)