fix: set object updatedAt on creation

Author: weakish

leancloud/object_.py

@@ -334,25 +334,18 @@ def _to_pointer(self):
         }
 
     def _merge_metadata(self, server_data):
-        for key in ("objectId", "createdAt", "updatedAt"):
-            if server_data.get(key) is None:
-                continue
-            if key == "objectId":
-                self.id = server_data[key]
-            else:
-                if isinstance(server_data[key], six.string_types):
-                    dt = utils.decode(key, {"__type": "Date", "iso": server_data[key]})
-                elif server_data[key]["__type"] == "Date":
-                    dt = utils.decode(key, server_data[key])
-                else:
-                    raise TypeError("Invalid date type")
-                server_data[key] = dt
-                if key == "createdAt":
-                    self.created_at = dt
-                elif key == "updatedAt":
-                    self.updated_at = dt
-                else:
-                    raise TypeError
+        object_id = server_data.get("objectId")
+        _created_at = utils.decode_date_string(server_data.get("createdAt"))
+        _updated_at = utils.decode_updated_at(server_data.get("updatedAt"), _created_at)
+
+        if object_id is not None:
+            self.id = object_id
+        if _created_at is not None:
+            self.created_at = _created_at
+        if _updated_at is not None:
+            self.updated_at = _updated_at
+
+
 
     def validate(self, attrs):
         if "ACL" in attrs and not isinstance(attrs["ACL"], leancloud.ACL):
@@ -370,6 +363,23 @@ def get(self, attr, default=None, deafult=None):
         # for backward compatibility
         if (deafult is not None) and (default is None):
             default = deafult
+
+        # createdAt is stored as string in the cloud but used as datetime object on the client side.
+        # We need to make sure that `.created_at` and `.get("createdAt")` return the same value.
+        # Otherwise users will get confused.
+        if attr == "createdAt":
+            if self.created_at is None:
+                return None
+            else:
+                return self.created_at
+
+        # Similar to createdAt.
+        if attr == "updatedAt":
+            if self.updated_at is None:
+                return None
+            else:
+                return self.updated_at
+        
         return self._attributes.get(attr, default)
 
     def relation(self, attr):

leancloud/utils.py

@@ -146,6 +146,32 @@ def decode(key, value):
         return f
 
 
+def decode_date_string(date_or_string):
+    if date_or_string is None:
+        return None
+    elif isinstance(date_or_string, six.string_types):
+        return decode_date_string({"__type": "Date", "iso": date_or_string})
+    elif date_or_string["__type"] == "Date":
+        return arrow.get(iso8601.parse_date(date_or_string["iso"])).to("local").datetime
+    else:
+        raise TypeError("Invalid date type")
+
+
+def decode_updated_at(updated_at_date_string, created_at_datetime):
+    updated_at = decode_date_string(updated_at_date_string)
+    if updated_at is None:
+        if created_at_datetime is None:
+            return None
+        else:
+            # When a new object is created, updatedAt will be set as the same value as createdAt on the cloud.
+            # However, the cloud will only return objectId and createdAt in REST API response, without updatedAt.
+            # Thus we need to set updatedAt as the same value as createdAt, consistent with the value on the cloud.
+            # This behaviour is consistent with other SDKs such as JavaScript and Go.
+            return created_at_datetime
+    else:
+        return updated_at
+
+
 def traverse_object(obj, callback, seen=None):
     seen = seen or set()
 

tests/test_object.py

@@ -314,6 +314,7 @@ def test_fetch_when_save():  # type: () -> None
     foo = Foo()
     foo.set("counter", 1)
     foo.save()
+    assert foo.created_at == foo.updated_at
     assert foo.get("counter") == 1
 
     foo_from_other_thread = leancloud.Query(Foo).get(foo.id)