Add a json_dump expression function

This is a new and simplified version of the json_pp function. It uses on
the standard jsonutils formatting and wont output the context if not
argument is provided.

Change-Id: I37f69d14e7cf4f57b910b355d7ccd31c9cd73d10

mistral/tests/unit/expressions/test_yaql_expression.py

@@ -15,11 +15,15 @@
 #    limitations under the License.
 
 import datetime
+import json
+import warnings
+
+import mock
+
 from mistral import exceptions as exc
 from mistral.expressions import yaql_expression as expr
 from mistral.tests.unit import base
 from mistral import utils
-import mock
 
 DATA = {
     "server": {
@@ -133,6 +137,34 @@ class YaqlEvaluatorTest(base.BaseTest):
             )
         )
 
+    def test_function_json_pp_deprecation(self):
+        with warnings.catch_warnings(record=True) as w:
+            result = self._evaluator.evaluate('json_pp($)', '3')
+            self.assertEqual('"3"', result)
+        self.assertEqual(len(w), 1)
+        self.assertTrue(issubclass(w[-1].category, DeprecationWarning))
+        self.assertTrue(str(w[-1].message).startswith(
+            "json_pp was deprecated in Queens and will be removed in the S "
+        ))
+
+    def test_function_json_dump(self):
+        self.assertEqual('"3"', self._evaluator.evaluate('json_dump($)', '3'))
+        self.assertEqual('3', self._evaluator.evaluate('json_dump($)', 3))
+        self.assertEqual(
+            json.dumps([1, 2], indent=4),
+            self._evaluator.evaluate('json_dump($)', [1, 2])
+        )
+        self.assertEqual(
+            json.dumps({"a": "b"}, indent=4),
+            self._evaluator.evaluate('json_dump($)', {'a': 'b'})
+        )
+        self.assertEqual(
+            json.dumps('\n'.join(["Mistral", "is", "awesome"]), indent=4),
+            self._evaluator.evaluate(
+                'json_dump($)', '\n'.join(['Mistral', 'is', 'awesome'])
+            )
+        )
+
     def test_function_uuid(self):
         uuid = self._evaluator.evaluate('uuid()', {})
 

mistral/utils/expression_utils.py

@@ -14,6 +14,7 @@
 #    limitations under the License.
 
 from functools import partial
+import warnings
 
 from oslo_serialization import jsonutils
 from stevedore import extension
@@ -116,12 +117,21 @@ def execution_(context):
 
 
 def json_pp_(context, data=None):
+    warnings.warn(
+        "json_pp was deprecated in Queens and will be removed in the S cycle. "
+        "The json_dump expression function can be used for outputting JSON",
+        DeprecationWarning
+    )
     return jsonutils.dumps(
         data or context,
         indent=4
     ).replace("\\n", "\n").replace(" \n", "\n")
 
 
+def json_dump_(context, data):
+    return jsonutils.dumps(data, indent=4)
+
+
 def yaml_dump_(context, data):
     return yaml.safe_dump(data, default_flow_style=False)
 

releasenotes/notes/add-json-dump-deprecate-json-pp-252c6c495fd2dea1.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    A new YAQL/jinja2 expression function has been added for outputting JSON.
+    It is json_dump and accepts one argument, which is the object to be
+    serialised to JSON.
+deprecations:
+  - |
+    The YAQL/jinja2 expression function ``json_pp`` has been deprecated and
+    will be removed in the S cycle. ``json_dump`` should be used instead.

setup.cfg

@@ -76,14 +76,17 @@ mistral.executors =
     remote = mistral.executors.remote_executor:RemoteExecutor
 
 mistral.expression.functions =
-    global = mistral.utils.expression_utils:global_
+    # json_pp was deprecated in Queens and will be removed in the S cycle
     json_pp = mistral.utils.expression_utils:json_pp_
+
+    env = mistral.utils.expression_utils:env_
+    execution = mistral.utils.expression_utils:execution_
+    global = mistral.utils.expression_utils:global_
+    json_parse = mistral.utils.expression_utils:json_parse_
+    json_dump = mistral.utils.expression_utils:json_dump_
     task = mistral.utils.expression_utils:task_
     tasks = mistral.utils.expression_utils:tasks_
-    execution = mistral.utils.expression_utils:execution_
-    env = mistral.utils.expression_utils:env_
     uuid = mistral.utils.expression_utils:uuid_
-    json_parse = mistral.utils.expression_utils:json_parse_
     yaml_parse = mistral.utils.expression_utils:yaml_parse_
 
 mistral.expression.evaluators =