From 8a6d22ccb53f14a26876a06152b7a3b47ae1a8e1 Mon Sep 17 00:00:00 2001
From: Brandon Logan <brandon.logan@rackspace.com>
Date: Wed, 8 Jun 2016 17:08:40 -0500
Subject: [PATCH] Pecan: handle single fields query parameter

This also correctly handles the case where no fields are requested which seems
to have started to break.

Closes-Bug: #1590588
Change-Id: Ida1e3ff575c7fe6c3199c5f4393679bbf89c0fe1
---
 neutron/pecan_wsgi/controllers/resource.py    |  6 +++-
 neutron/pecan_wsgi/controllers/utils.py       |  4 ++-
 .../functional/pecan_wsgi/test_controllers.py | 29 +++++++++++++++----
 3 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/neutron/pecan_wsgi/controllers/resource.py b/neutron/pecan_wsgi/controllers/resource.py
index 20b287bd5c6..c3ab68b504c 100644
--- a/neutron/pecan_wsgi/controllers/resource.py
+++ b/neutron/pecan_wsgi/controllers/resource.py
@@ -100,7 +100,11 @@ class CollectionsController(utils.NeutronPecanController):
 
     def get(self, *args, **kwargs):
         # list request
-        fields = self._build_field_list(kwargs.pop('fields', []))
+        fields = kwargs.pop('fields', [])
+        # if only one fields query parameter is passed, pecan will not put
+        # that parameter in a list, so we need to convert it into a list
+        fields = fields if isinstance(fields, list) else [fields]
+        fields = self._build_field_list(fields)
         _listify = lambda x: x if isinstance(x, list) else [x]
         filters = api_common.get_filters_from_dict(
             {k: _listify(v) for k, v in kwargs.items()},
diff --git a/neutron/pecan_wsgi/controllers/utils.py b/neutron/pecan_wsgi/controllers/utils.py
index 70b690f8c14..6ee19e3ea04 100644
--- a/neutron/pecan_wsgi/controllers/utils.py
+++ b/neutron/pecan_wsgi/controllers/utils.py
@@ -103,7 +103,9 @@ class NeutronPecanController(object):
             self._mandatory_fields = set()
 
     def _build_field_list(self, request_fields):
-        return set(request_fields) | self._mandatory_fields
+        if request_fields:
+            return set(request_fields) | self._mandatory_fields
+        return []
 
     @property
     def plugin(self):
diff --git a/neutron/tests/functional/pecan_wsgi/test_controllers.py b/neutron/tests/functional/pecan_wsgi/test_controllers.py
index 3a02e303adb..2f083103d6b 100644
--- a/neutron/tests/functional/pecan_wsgi/test_controllers.py
+++ b/neutron/tests/functional/pecan_wsgi/test_controllers.py
@@ -263,14 +263,31 @@ class TestResourceController(TestRootController):
             self.assertIn(attribute, item)
         self.assertEqual(len(expected), len(item))
 
-    def test_get_collection_with_fields_selector(self):
-        list_resp = self.app.get('/v2.0/ports.json?fields=id&fields=name',
-                                 headers={'X-Project-Id': 'tenid'})
+    def _test_get_collection_with_fields_selector(self, fields=None):
+        fields = fields or []
+        query_params = ['fields=%s' % field for field in fields]
+        url = '/v2.0/ports.json'
+        if query_params:
+            url = '%s?%s' % (url, '&'.join(query_params))
+        list_resp = self.app.get(url, headers={'X-Project-Id': 'tenid'})
         self.assertEqual(200, list_resp.status_int)
         for item in jsonutils.loads(list_resp.body).get('ports', []):
-            self.assertIn('id', item)
-            self.assertIn('name', item)
-            self.assertEqual(2, len(item))
+            for field in fields:
+                self.assertIn(field, item)
+            if fields:
+                self.assertEqual(len(fields), len(item))
+            else:
+                for field in ('id', 'name', 'device_owner'):
+                    self.assertIn(field, item)
+
+    def test_get_collection_with_multiple_fields_selector(self):
+        self._test_get_collection_with_fields_selector(fields=['id', 'name'])
+
+    def test_get_collection_with_single_fields_selector(self):
+        self._test_get_collection_with_fields_selector(fields=['name'])
+
+    def test_get_collection_without_fields_selector(self):
+        self._test_get_collection_with_fields_selector(fields=[])
 
     def test_get_item_with_fields_selector(self):
         item_resp = self.app.get(