Merge lp:~mpontillo/maas/subnet-list-nonetype--bug-1599997--2.0 into lp:maas/2.0

[Mike Pontillo]

Backport revision 5160 from trunk to fix issue where NULL dns_servers field in subnet websocket handler was handled improperly. Update changelog.

[Mike Pontillo (mpontillo)]

Self-approving backport.

review: Approve

=== modified file 'docs/changelog.rst'
--- docs/changelog.rst	2016-07-01 03:06:12 +0000
+++ docs/changelog.rst	2016-07-07 22:48:43 +0000
@@ -2,6 +2,12 @@
 Changelog
 =========
 
+2.0.0 (rc2)
+===========
+
+LP: #1599997    [2.0rc1] after upgrade from 2.0b3, Error on request (13) subnet.list: 'NoneType' object is not iterable
+
+
 2.0.0 (rc1)
 ===========
 
 
=== modified file 'src/maasserver/websockets/handlers/subnet.py'
--- src/maasserver/websockets/handlers/subnet.py	2016-05-11 19:01:48 +0000
+++ src/maasserver/websockets/handlers/subnet.py	2016-07-07 22:48:43 +0000
@@ -43,6 +43,8 @@
         ]
 
     def dehydrate_dns_servers(self, dns_servers):
+        if dns_servers is None:
+            return ""
         return " ".join(sorted(dns_servers))
 
     def dehydrate(self, subnet, data, for_list=False):
 
=== modified file 'src/maasserver/websockets/handlers/tests/test_subnet.py'
--- src/maasserver/websockets/handlers/tests/test_subnet.py	2016-05-12 19:07:37 +0000
+++ src/maasserver/websockets/handlers/tests/test_subnet.py	2016-07-07 22:48:43 +0000
@@ -26,7 +26,10 @@
             "created": dehydrate_datetime(subnet.created),
             "name": subnet.name,
             "description": subnet.description,
-            "dns_servers": " ".join(sorted(subnet.dns_servers)),
+            "dns_servers": (
+                " ".join(sorted(subnet.dns_servers))
+                if subnet.dns_servers is not None else ''
+            ),
             "vlan": subnet.vlan_id,
             "space": subnet.space_id,
             "rdns_mode": subnet.rdns_mode,
@@ -52,6 +55,16 @@
         result = handler.get({"id": subnet.id})
         self.assertThat(result, Equals(expected_data))
 
+    def test_get_handles_null_dns_servers(self):
+        user = factory.make_User()
+        handler = SubnetHandler(user, {})
+        subnet = factory.make_Subnet()
+        subnet.dns_servers = None
+        subnet.save()
+        expected_data = self.dehydrate_subnet(subnet)
+        result = handler.get({"id": subnet.id})
+        self.assertThat(result, Equals(expected_data))
+
     def test_list(self):
         user = factory.make_User()
         handler = SubnetHandler(user, {})