Merge ~ack/maas:1923251-driver-char-field-use-default into maas:master

[Alberto Donato]

LP: 1923251 - set empty_value for CharField default in pod drivers

This fixes the linked by always passing a value for "project" (which must be
set), falling back to the default when no value is specified.

[MAAS Lander (maas-lander)]

UNIT TESTS
-b 1923251-driver-char-field-use-default lp:~ack/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: FAILED
LOG: http://maas-ci.internal:8080/job/maas/job/branch-tester/9731/console
COMMIT: 54a1d123c248e9bf433a6cc5b0d6261453f14d28

review: Needs Fixing

[Adam Collard (adam-collard)]

Add a test for the specific case? i.e. API request omitting project uses default

[Alberto Donato (ack)]

Updated (and fixed logic for test failure). thanks

[MAAS Lander (maas-lander)]

UNIT TESTS
-b 1923251-driver-char-field-use-default lp:~ack/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: FAILED
LOG: http://maas-ci.internal:8080/job/maas/job/branch-tester/9733/console
COMMIT: 365a6262a2cb5422f49c4340ee2b9a9a5183f9dd

review: Needs Fixing

[Adam Collard (adam-collard)]

review: Approve

diff --git a/src/maasserver/api/tests/test_pods.py b/src/maasserver/api/tests/test_pods.py
index fb07c8e..0fb4965 100644
--- a/src/maasserver/api/tests/test_pods.py
+++ b/src/maasserver/api/tests/test_pods.py
@@ -198,6 +198,22 @@ class TestPodsAPIAdmin(PodAPITestForAdmin, PodMixin):
         parsed_result = json_load_bytes(response.content)
         self.assertEqual(parsed_result["type"], pod_info["type"])
 
+    def test_create_lxd_default_project(self):
+        self.patch(pods, "post_commit_do")
+        discovered_pod, _, _ = self.fake_pod_discovery()
+        ip = factory.make_ipv4_address()
+        info = {
+            "type": "lxd",
+            "power_address": ip,
+            "power_pass": "sekret",
+            "ip_address": ip,
+        }
+        response = self.client.post(reverse("pods_handler"), info)
+        self.assertEqual(http.client.OK, response.status_code)
+        parsed_result = json_load_bytes(response.content)
+        pod = Pod.objects.get(id=parsed_result["id"])
+        self.assertEqual(pod.power_parameters["project"], "default")
+
     def test_create_creates_pod_with_default_resource_pool(self):
         self.patch(pods, "post_commit_do")
         discovered_pod, _, _ = self.fake_pod_discovery()
diff --git a/src/maasserver/clusterrpc/driver_parameters.py b/src/maasserver/clusterrpc/driver_parameters.py
index 3f5a3a5..440075a 100644
--- a/src/maasserver/clusterrpc/driver_parameters.py
+++ b/src/maasserver/clusterrpc/driver_parameters.py
@@ -75,13 +75,14 @@ def make_form_field(json_field):
         extra_parameters = {}
 
     default = json_field.get("default")
+    required = json_field.get("required")
     if default is not None:
         extra_parameters["initial"] = default
+        if required and field_class is forms.CharField:
+            extra_parameters["empty_value"] = default
 
     form_field = field_class(
-        label=json_field["label"],
-        required=json_field["required"],
-        **extra_parameters
+        label=json_field["label"], required=required, **extra_parameters
     )
     return form_field
 
diff --git a/src/maasserver/clusterrpc/tests/test_driver_parameters.py b/src/maasserver/clusterrpc/tests/test_driver_parameters.py
index 9356a86..d9728c7 100644
--- a/src/maasserver/clusterrpc/tests/test_driver_parameters.py
+++ b/src/maasserver/clusterrpc/tests/test_driver_parameters.py
@@ -204,7 +204,7 @@ class TestMakeFormField(MAASServerTestCase):
             (django_field.label, django_field.required),
         )
 
-    def test_sets_initial_to_default(self):
+    def test_sets_default_not_required(self):
         json_field = {
             "name": "some_field",
             "label": "Some Field",
@@ -213,7 +213,20 @@ class TestMakeFormField(MAASServerTestCase):
             "default": "some default",
         }
         django_field = make_form_field(json_field)
-        self.assertEqual(json_field["default"], django_field.initial)
+        self.assertEqual("some default", django_field.initial)
+        self.assertEqual("", django_field.empty_value)
+
+    def test_sets_default_and_empty_value_required(self):
+        json_field = {
+            "name": "some_field",
+            "label": "Some Field",
+            "field_type": "string",
+            "required": True,
+            "default": "some default",
+        }
+        django_field = make_form_field(json_field)
+        self.assertEqual("some default", django_field.initial)
+        self.assertEqual("some default", django_field.empty_value)
 
 
 class TestMakeSettingField(MAASServerTestCase):
diff --git a/src/maasserver/forms/pods.py b/src/maasserver/forms/pods.py
index cfedaac..2fbc1ff 100644
--- a/src/maasserver/forms/pods.py
+++ b/src/maasserver/forms/pods.py
@@ -222,7 +222,7 @@ class PodForm(MAASModelForm):
             for driver in self.drivers_orig
             if driver["driver_type"] == "pod"
         }
-        if len(self.drivers) == 0:
+        if not self.drivers:
             type_value = ""
         elif type_value not in self.drivers:
             type_value = (
@@ -256,7 +256,7 @@ class PodForm(MAASModelForm):
         super()._clean_fields()
         # If no errors then we re-process with the fields required by the
         # selected type for the pod.
-        if len(self.errors) == 0:
+        if not self.errors:
             driver_fields = get_driver_parameters_from_json(
                 self.drivers_orig, scope=SETTING_SCOPE.BMC
             )
@@ -272,7 +272,7 @@ class PodForm(MAASModelForm):
 
     def clean(self):
         cleaned_data = super().clean()
-        if len(self.drivers) == 0:
+        if not self.drivers:
             set_form_error(
                 self,
                 "type",