Merge ~ack/maas:1993152-pod-form-keep-tags into maas:master

[Alberto Donato]

LP:1993152 keep current tags in PodForm when not specified in posted data

[MAAS Lander (maas-lander)]

UNIT TESTS
-b 1993152-pod-form-keep-tags lp:~ack/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: FAILED
LOG: http://maas-ci.internal:8080/job/maas-tester/1306/consoleText
COMMIT: 202ad7487407857fa0f02d43a20fd8ad8631fd34

review: Needs Fixing

[Alberto Donato (ack)]

jenkins: !test

[MAAS Lander (maas-lander)]

UNIT TESTS
-b 1993152-pod-form-keep-tags lp:~ack/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: SUCCESS
COMMIT: 202ad7487407857fa0f02d43a20fd8ad8631fd34

review: Approve

[Jack Lloyd-Walters (lloydwaltersj)]

+1

review: Approve

[MAAS Lander (maas-lander)]

LANDING
-b 1993152-pod-form-keep-tags lp:~ack/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://maas-ci.internal:8080/job/maas-tester/1316/consoleText

[MAAS Lander (maas-lander)]

LANDING
-b 1993152-pod-form-keep-tags lp:~ack/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://maas-ci.internal:8080/job/maas-tester/1317/consoleText

diff --git a/src/maasserver/api/tests/test_nodes.py b/src/maasserver/api/tests/test_nodes.py
index e124d74..88fa7e6 100644
--- a/src/maasserver/api/tests/test_nodes.py
+++ b/src/maasserver/api/tests/test_nodes.py
@@ -188,7 +188,9 @@ class RequestFixture:
         if user is None:
             user = factory.make_User()
         self.user = user
-        self.GET = get_overridden_query_dict(dict, QueryDict(""), fields)
+        self.GET = get_overridden_query_dict(
+            dict, QueryDict(mutable=True), fields
+        )
 
 
 class TestFilteredNodesListFromRequest(APITestCase.ForUser):
diff --git a/src/maasserver/api/utils.py b/src/maasserver/api/utils.py
index 3613011..43e363b 100644
--- a/src/maasserver/api/utils.py
+++ b/src/maasserver/api/utils.py
@@ -155,8 +155,7 @@ def get_overridden_query_dict(defaults, data, fields):
     :return: The updated QueryDict.
     :raises: :class:`django.http.QueryDict`
     """
-    # Create a writable query dict.
-    new_data = QueryDict("").copy()
+    new_data = QueryDict(mutable=True)
     # If the fields are a dict of django Fields see if one is a DictCharField.
     # DictCharField must have their values prefixed with the DictField name in
     # the returned data or defaults don't get carried.
diff --git a/src/maasserver/forms/pods.py b/src/maasserver/forms/pods.py
index 05cb103..27c2970 100644
--- a/src/maasserver/forms/pods.py
+++ b/src/maasserver/forms/pods.py
@@ -197,6 +197,8 @@ class PodForm(MAASModelForm):
             if self.instance.power_type != "":
                 self.initial["type"] = self.instance.power_type
         if instance is not None:
+            # tags must be passed as a comma-separated value, not a list
+            self.initial["tags"] = ",".join(instance.tags)
             self.initial["zone"] = instance.zone.name
             self.initial["pool"] = instance.pool.name
             self.fields[
diff --git a/src/maasserver/forms/tests/test_pods.py b/src/maasserver/forms/tests/test_pods.py
index b7c4e74..9a4dd86 100644
--- a/src/maasserver/forms/tests/test_pods.py
+++ b/src/maasserver/forms/tests/test_pods.py
@@ -365,6 +365,18 @@ class TestPodForm(MAASTransactionServerTestCase):
         self.assertEqual(pod.pool, pool)
         self.assertEqual(pod.name, new_name)
 
+    def test_updates_existing_pod_keeps_tags(self):
+        tags = ["foo", "bar", "pod-console-logging"]
+        pod = factory.make_Pod(tags=tags)
+        form = PodForm(
+            data={"name": factory.make_name("pod")},
+            request=self.request,
+            instance=pod,
+        )
+        self.assertTrue(form.is_valid(), form._errors)
+        pod = form.save()
+        self.assertCountEqual(pod.tags, tags)
+
     def test_updates_default_storage_pool(self):
         discovered_pod = self.make_discovered_pod()
         default_storage_pool = random.choice(discovered_pod.storage_pools)