From fc9871fba3af578197576a141a6830596fdc0d78 Mon Sep 17 00:00:00 2001
From: Jeremy Stretch <jstretch@digitalocean.com>
Date: Thu, 1 Mar 2018 11:57:04 -0500
Subject: [PATCH] Fixes #1935: Correct API validation of VLANs assigned to
 interfaces

---
 netbox/dcim/api/serializers.py | 21 +++++++++++++--------
 netbox/utilities/api.py        |  2 +-
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/netbox/dcim/api/serializers.py b/netbox/dcim/api/serializers.py
index edcd93ef247..ea87c409803 100644
--- a/netbox/dcim/api/serializers.py
+++ b/netbox/dcim/api/serializers.py
@@ -731,15 +731,20 @@ class Meta:
 
     def validate(self, data):
 
-        # Validate that all untagged VLANs either belong to the same site as the Interface's parent Deivce or
-        # VirtualMachine, or are global.
-        parent = self.instance.parent if self.instance else data.get('device') or data.get('virtual_machine')
+        # All associated VLANs be global or assigned to the parent device's site.
+        device = self.instance.device if self.instance else data.get('device')
+        untagged_vlan = data.get('untagged_vlan')
+        if untagged_vlan and untagged_vlan.site not in [device.site, None]:
+            raise serializers.ValidationError({
+                'untagged_vlan': "VLAN {} must belong to the same site as the interface's parent device, or it must be "
+                                 "global.".format(untagged_vlan)
+            })
         for vlan in data.get('tagged_vlans', []):
-            if vlan.site not in [parent, None]:
-                raise serializers.ValidationError(
-                    "Tagged VLAN {} must belong to the same site as the interface's parent device/VM, or it must be "
-                    "global".format(vlan)
-                )
+            if vlan.site not in [device.site, None]:
+                raise serializers.ValidationError({
+                    'tagged_vlans': "VLAN {} must belong to the same site as the interface's parent device, or it must "
+                                   "be global.".format(vlan)
+                })
 
         return super(WritableInterfaceSerializer, self).validate(data)
 
diff --git a/netbox/utilities/api.py b/netbox/utilities/api.py
index 8471d0e00c7..5c78dacc4c9 100644
--- a/netbox/utilities/api.py
+++ b/netbox/utilities/api.py
@@ -55,7 +55,7 @@ def validate(self, data):
             model = self.Meta.model
             # Ignore ManyToManyFields for new instances (a PK is needed for validation)
             for field in model._meta.get_fields():
-                if isinstance(field, ManyToManyField):
+                if isinstance(field, ManyToManyField) and field.name in attrs:
                     attrs.pop(field.name)
             instance = self.Meta.model(**attrs)
         else: