Merge pull request #174 from highcharts-for-python/develop

PR for v.1.7.4

Author: hcpchris

CHANGES.rst

@@ -1,4 +1,12 @@
 
+Release 1.7.4
+=========================================
+
+* **BUGFIX:** Fixed incorrect ``.to_json()`` serialization of ``null`` values inside of an iterable.
+
+--------------------
+
+
 Release 1.7.3
 =========================================
 

highcharts_core/__version__.py

@@ -1 +1 @@
-__version__ = '1.7.3'
+__version__ = '1.7.4'

highcharts_core/metaclasses.py

@@ -230,7 +230,10 @@ def trim_iterable(untrimmed,
             if checkers.is_type(item, 'CallbackFunction') and to_json:
                 continue
             elif item is None or item == constants.EnforcedNull:
-                trimmed.append('null')
+                if to_json:
+                    trimmed.append(None)
+                else:
+                    trimmed.append('null')
             elif hasattr(item, 'trim_dict'):
                 updated_context = item.__class__.__name__
                 untrimmed_item = item._to_untrimmed_dict()