Fix next link in get resource list rest API

Fix the issue where `next` link in the response of the REST API, when
used with pagination, gets corrupted and makes it unusable. After this
fix, next link should be readily usable.

Change-Id: Idf45a59e0b07d8306cc82391679fe30a9cd2f0c1
Closes-Bug: #1793344

mistral/api/controllers/resource.py

@@ -115,9 +115,14 @@ class ResourceList(Resource):
         if not self.has_next(limit):
             return wtypes.Unset
 
-        q_args = ''.join(
-            ['%s=%s&' % (key, value) for key, value in kwargs.items()]
-        )
+        q_args = ''
+
+        for key, value in kwargs.items():
+            if isinstance(value, dict):
+                q_args += '%s=%s:%s&' % \
+                          (key, list(value.keys())[0], list(value.values())[0])
+            else:
+                q_args += '%s=%s&' % (key, value)
 
         resource_args = (
             '?%(args)slimit=%(limit)d&marker=%(marker)s' %

mistral/tests/unit/api/test_resource_list.py

@@ -0,0 +1,38 @@
+# Copyright 2018 Nokia Networks. All rights reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from oslotest import base
+
+from mistral.api.controllers.v2 import resources
+
+
+class TestResourceList(base.BaseTestCase):
+
+    def test_next_link_correctness(self):
+        task = resources.Task.sample()
+
+        result = resources.Tasks.convert_with_links(
+            resources=[task],
+            limit=1,
+            url='https://localhost:8080',
+            sort_keys='created_at,id',
+            sort_dirs='asc,asc',
+            fields='',
+            state='eq:RUNNING'
+        )
+
+        next_link = result.next
+
+        self.assertIn('state=eq:RUNNING', next_link)
+        self.assertIn('sort_keys=created_at,id', next_link)

releasenotes/notes/fix-next-url-formatting-2cc0d8a27625c73a.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    Fix issue where next link in some list APIs,
+    when invoked with pagination and filter(s),
+    contained JSON string. This made next link
+    an invalid URL. This issue impacted all REST
+    APIs where filters can be used.
+