Add to/from json methods to Credentials classes

This adds to_json and from_json methods to GoogleCredentials
and _ServiceAccountCredentials classes. This allows them to
be serialized by multistore_file.

Resolves: #384

oauth2client/client.py

@@ -198,6 +198,13 @@ class MemoryCache(object):
         self.cache.pop(key, None)
 
 
+def _parse_expiry(expiry):
+    if expiry and isinstance(expiry, datetime.datetime):
+        return expiry.strftime(EXPIRY_FORMAT)
+    else:
+        return None
+
+
 class Credentials(object):
     """Base class for all Credentials objects.
 
@@ -208,7 +215,7 @@ class Credentials(object):
     JSON string as input and returns an instantiated Credentials object.
     """
 
-    NON_SERIALIZED_MEMBERS = ['store']
+    NON_SERIALIZED_MEMBERS = frozenset(['store'])
 
     def authorize(self, http):
         """Take an httplib2.Http instance (or equivalent) and authorizes it.
@@ -265,9 +272,7 @@ class Credentials(object):
         for member in strip:
             if member in d:
                 del d[member]
-        if (d.get('token_expiry') and
-                isinstance(d['token_expiry'], datetime.datetime)):
-            d['token_expiry'] = d['token_expiry'].strftime(EXPIRY_FORMAT)
+        d['token_expiry'] = _parse_expiry(d.get('token_expiry'))
         # Add in information we will need later to reconsistitue this instance.
         d['_class'] = t.__name__
         d['_module'] = t.__module__
@@ -285,7 +290,7 @@ class Credentials(object):
             string, a JSON representation of this instance, suitable to pass to
             from_json().
         """
-        return self._to_json(Credentials.NON_SERIALIZED_MEMBERS)
+        return self._to_json(self.NON_SERIALIZED_MEMBERS)
 
     @classmethod
     def new_from_json(cls, s):
@@ -699,9 +704,6 @@ class OAuth2Credentials(Credentials):
         self._retrieve_scopes(http.request)
         return self.scopes
 
-    def to_json(self):
-        return self._to_json(Credentials.NON_SERIALIZED_MEMBERS)
-
     @classmethod
     def from_json(cls, s):
         """Instantiate a Credentials object from a JSON description of it.
@@ -1180,6 +1182,11 @@ class GoogleCredentials(OAuth2Credentials):
         print(response)
     """
 
+    NON_SERIALIZED_MEMBERS =  (
+        frozenset(['_private_key']) |
+        OAuth2Credentials.NON_SERIALIZED_MEMBERS)
+
+
     def __init__(self, access_token, client_id, client_secret, refresh_token,
                  token_expiry, token_uri, user_agent,
                  revoke_uri=GOOGLE_REVOKE_URI):
@@ -1222,6 +1229,32 @@ class GoogleCredentials(OAuth2Credentials):
         """
         return self
 
+    @classmethod
+    def from_json(cls, s):
+        # TODO(issue 388): eliminate the circularity that is the reason for
+        # this non-top-level import.
+        from oauth2client.service_account import _ServiceAccountCredentials
+        data = json.loads(_from_bytes(s))
+
+        # We handle service_account._ServiceAccountCredentials since it is a
+        # possible return type of GoogleCredentials.get_application_default()
+        if (data['_module'] == 'oauth2client.service_account' and
+            data['_class'] == '_ServiceAccountCredentials'):
+            return _ServiceAccountCredentials.from_json(s)
+
+        token_expiry = _parse_expiry(data.get('token_expiry'))
+        google_credentials = cls(
+            data['access_token'],
+            data['client_id'],
+            data['client_secret'],
+            data['refresh_token'],
+            token_expiry,
+            data['token_uri'],
+            data['user_agent'],
+            revoke_uri=data.get('revoke_uri', None))
+        google_credentials.invalid = data['invalid']
+        return google_credentials
+
     @property
     def serialization_data(self):
         """Get the fields and values identifying the current credentials."""

oauth2client/service_account.py

@@ -18,6 +18,8 @@ This credentials class is implemented on top of rsa library.
 """
 
 import base64
+import datetime
+import json
 import time
 
 from pyasn1.codec.ber import decoder
@@ -27,10 +29,12 @@ import rsa
 from oauth2client import GOOGLE_REVOKE_URI
 from oauth2client import GOOGLE_TOKEN_URI
 from oauth2client._helpers import _json_encode
+from oauth2client._helpers import _from_bytes
 from oauth2client._helpers import _to_bytes
 from oauth2client._helpers import _urlsafe_b64encode
 from oauth2client import util
 from oauth2client.client import AssertionCredentials
+from oauth2client.client import EXPIRY_FORMAT
 
 
 class _ServiceAccountCredentials(AssertionCredentials):
@@ -38,6 +42,11 @@ class _ServiceAccountCredentials(AssertionCredentials):
 
     MAX_TOKEN_LIFETIME_SECS = 3600  # 1 hour in seconds
 
+    NON_SERIALIZED_MEMBERS =  (
+        frozenset(['_private_key']) |
+        AssertionCredentials.NON_SERIALIZED_MEMBERS)
+
+
     def __init__(self, service_account_id, service_account_email,
                  private_key_id, private_key_pkcs8_text, scopes,
                  user_agent=None, token_uri=GOOGLE_TOKEN_URI,
@@ -108,6 +117,25 @@ class _ServiceAccountCredentials(AssertionCredentials):
             'private_key': self._private_key_pkcs8_text
         }
 
+    @classmethod
+    def from_json(cls, s):
+        data = json.loads(_from_bytes(s))
+
+        credentials = cls(
+            service_account_id=data['_service_account_id'],
+            service_account_email=data['_service_account_email'],
+            private_key_id=data['_private_key_id'],
+            private_key_pkcs8_text=data['_private_key_pkcs8_text'],
+            scopes=[],
+            user_agent=data['_user_agent'])
+        credentials.invalid = data['invalid']
+        credentials.access_token = data['access_token']
+        token_expiry = data.get('token_expiry', None)
+        if token_expiry is not None:
+            credentials.token_expiry = datetime.datetime.strptime(
+                token_expiry, EXPIRY_FORMAT)
+        return credentials
+
     def create_scoped_required(self):
         return not self._scopes
 

tests/test_client.py

@@ -618,6 +618,35 @@ class GoogleCredentialsTests(unittest2.TestCase):
             self.get_a_google_credentials_object().from_stream,
             credentials_file)
 
+    def test_to_from_json_authorized_user(self):
+        credentials_file = datafile(
+            os.path.join('gcloud', 'application_default_credentials_authorized_user.json'))
+        creds = GoogleCredentials.from_stream(credentials_file)
+        json = creds.to_json()
+        creds2 = GoogleCredentials.from_json(json)
+
+        self.assertEqual(creds.__dict__, creds2.__dict__)
+
+    def test_to_from_json_service_account(self):
+        self.maxDiff=None
+        credentials_file = datafile(
+            os.path.join('gcloud', _WELL_KNOWN_CREDENTIALS_FILE))
+        creds = GoogleCredentials.from_stream(credentials_file)
+
+        json = creds.to_json()
+        creds2 = GoogleCredentials.from_json(json)
+
+        self.assertEqual(creds.__dict__, creds2.__dict__)
+
+    def test_parse_expiry(self):
+        dt = datetime.datetime(2016, 1, 1)
+        parsed_expiry = client._parse_expiry(dt)
+        self.assertEqual('2016-01-01T00:00:00Z', parsed_expiry)
+
+    def test_bad_expiry(self):
+        dt = object()
+        parsed_expiry = client._parse_expiry(dt)
+        self.assertEqual(None, parsed_expiry)
 
 class DummyDeleteStorage(Storage):
     delete_called = False
@@ -774,6 +803,12 @@ class BasicCredentialsTests(unittest2.TestCase):
         instance = OAuth2Credentials.from_json(json.dumps(data))
         self.assertTrue(isinstance(instance, OAuth2Credentials))
 
+    def test_from_json_bad_token_expiry(self):
+        data = json.loads(self.credentials.to_json())
+        data['token_expiry'] = 'foobar'
+        instance = OAuth2Credentials.from_json(json.dumps(data))
+        self.assertTrue(isinstance(instance, OAuth2Credentials))
+
     def test_unicode_header_checks(self):
         access_token = u'foo'
         client_id = u'some_client_id'