From 82017411beb12717780d036f7308086d8fe37ef5 Mon Sep 17 00:00:00 2001
From: Sam Smith <samsmith@linux.vnet.ibm.com>
Date: Mon, 9 Jul 2018 16:00:46 +0100
Subject: [PATCH] Add custom JSON encoder/decoder option to `Document`
 constructor

---
 CHANGES.md                   |  1 +
 src/cloudant/document.py     |  9 +++++---
 tests/unit/document_tests.py | 44 ++++++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index 1ca11aa0..3c3e925a 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,6 @@
 # Unreleased
 
+- [NEW] Add custom JSON encoder/decoder option to `Document` constructor.
 - [NEW] Add new view parameters, `stable` and `update`, as keyword arguments to `get_view_result`.
 - [FIXED] Case where an exception was raised after successful retry when using `doc.update_field`.
 
diff --git a/src/cloudant/document.py b/src/cloudant/document.py
index 768ecca5..7feda18a 100644
--- a/src/cloudant/document.py
+++ b/src/cloudant/document.py
@@ -53,8 +53,10 @@ class Document(dict):
     :param database: A database instance used by the Document.  Can be
         either a ``CouchDatabase`` or ``CloudantDatabase`` instance.
     :param str document_id: Optional document id used to identify the document.
+    :param str encoder: Optional JSON encoder object.
+    :param str decoder: Optional JSON decoder object.
     """
-    def __init__(self, database, document_id=None):
+    def __init__(self, database, document_id=None, **kwargs):
         super(Document, self).__init__()
         self._client = database.client
         self._database = database
@@ -63,7 +65,8 @@ def __init__(self, database, document_id=None):
         self._document_id = document_id
         if self._document_id is not None:
             self['_id'] = self._document_id
-        self.encoder = self._client.encoder
+        self.encoder = kwargs.get('encoder') or self._client.encoder
+        self.decoder = kwargs.get('decoder') or json.JSONDecoder
 
     @property
     def r_session(self):
@@ -165,7 +168,7 @@ def fetch(self):
         resp = self.r_session.get(self.document_url)
         resp.raise_for_status()
         self.clear()
-        self.update(resp.json())
+        self.update(resp.json(cls=self.decoder))
 
     def save(self):
         """
diff --git a/tests/unit/document_tests.py b/tests/unit/document_tests.py
index dd443ccf..3c7b5afc 100644
--- a/tests/unit/document_tests.py
+++ b/tests/unit/document_tests.py
@@ -30,6 +30,8 @@
 import uuid
 import inspect
 
+from datetime import datetime
+
 from cloudant.document import Document
 from cloudant.error import CloudantDocumentException
 
@@ -859,5 +861,47 @@ def test_document_request_fails_after_client_disconnects(self):
         finally:
             self.client.connect()
 
+    def test_document_custom_json_encoder_and_decoder(self):
+        dt_format = '%Y-%m-%dT%H:%M:%S'
+
+        class DTEncoder(json.JSONEncoder):
+
+            def default(self, obj):
+                if isinstance(obj, datetime):
+                    return {
+                        '_type': 'datetime',
+                        'value': obj.strftime(dt_format)
+                    }
+                return super(DTEncoder, self).default(obj)
+
+        class DTDecoder(json.JSONDecoder):
+
+            def __init__(self, *args, **kwargs):
+                json.JSONDecoder.__init__(self, object_hook=self.object_hook,
+                                          *args, **kwargs)
+
+            def object_hook(self, obj):
+                if '_type' not in obj:
+                    return obj
+                if obj['_type'] == 'datetime':
+                    return datetime.strptime(obj['value'], dt_format)
+                return obj
+
+        doc = Document(self.db, encoder=DTEncoder)
+        doc['name'] = 'julia'
+        doc['dt'] = datetime(2018, 7, 9, 15, 11, 10, 0)
+        doc.save()
+
+        raw_doc = self.db.all_docs(include_docs=True)['rows'][0]['doc']
+
+        self.assertEquals(raw_doc['name'], 'julia')
+        self.assertEquals(raw_doc['dt']['_type'], 'datetime')
+        self.assertEquals(raw_doc['dt']['value'], '2018-07-09T15:11:10')
+
+        doc2 = Document(self.db, doc['_id'], decoder=DTDecoder)
+        doc2.fetch()
+
+        self.assertEquals(doc2['dt'], doc['dt'])
+
 if __name__ == '__main__':
     unittest.main()