JSON datetime test

test/json/json_datetime.py

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+###############################################################################
+##
+##  Copyright 2011 Tavendo GmbH
+##
+##  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.
+##
+###############################################################################
+
+import json, datetime
+from json.decoder import scanstring, py_scanstring
+from json.scanner import make_scanner, py_make_scanner
+
+ISO_TIMESTAMP_FORMAT = "%Y-%m-%dT%H:%M:%SZ"
+
+
+## There are a couple of problems with this code. The main one is a consequence
+## of the lack of parse_string argument in JSONDecoder constructor in Python.
+##
+## 1) it does not support the whole ISO 8601
+## 2) JSONDecoder can take i.e. parse_float, but not parse_string in __init__
+##    to hook in custom string parser.
+## 3) JSONDecoder has a self.parse_string internally, but override only works
+##    when using py_make_scanner, not C-based make_scanner
+## 4) The custom_parse_string is naive: it will just try to convert any string
+##    to datetime, and if it works, will provide that.
+##
+
+
+class CustomJSONEncoder(json.JSONEncoder):
+
+   def default(self, obj):
+      if isinstance(obj, datetime.datetime):
+         return obj.strftime(ISO_TIMESTAMP_FORMAT)
+      else:
+         return json.JSONEncoder.default(self, obj)
+
+
+def custom_parse_string(string, idx, encoding, strict):
+   obj = scanstring(string, idx, encoding, strict)
+   if type(obj[0]) in [str, unicode]:
+      try:
+         dt = datetime.datetime.strptime(obj[0], ISO_TIMESTAMP_FORMAT)
+         return [dt, obj[1]]
+      except:
+         pass
+   return obj
+
+
+class CustomJSONDecoder(json.JSONDecoder):
+
+   def __init__(self, encoding=None, object_hook=None, parse_float=None,
+                parse_int=None, parse_constant=None, strict=True,
+                object_pairs_hook=None):
+      json.JSONDecoder.__init__(self, encoding, object_hook, parse_float, parse_int, parse_constant, strict, object_pairs_hook)
+      self.parse_string = custom_parse_string
+      #self.scan_once = make_scanner(self)  # using C-based variant does not work
+      self.scan_once = py_make_scanner(self)
+
+
+if __name__ == '__main__':
+
+   objs = [
+        "sdlkjfh",
+        datetime.datetime.utcnow(),
+        [datetime.datetime.utcnow(), 5, 6],
+        {'foo': 23,
+        'goo': datetime.datetime.utcnow(),
+        'zoo': [1, 2, 3, datetime.datetime.utcnow(), 4, 5],
+        'koo': {'x1': datetime.datetime.utcnow(), 'x2': 666}}]
+
+   for o in objs:
+      print o
+      s = json.dumps(o, cls = CustomJSONEncoder)
+      print s
+      o2 = json.loads(s, cls = CustomJSONDecoder)
+      print o2