serializable ObjectId

[doncatnip]

Hey hey

It would be awesome if ObjectId's are nativeley (re)serializable. E.g. to embed them in json return values of json-rpc handlers. That way, one can avoid iterating over docs to replace certain objects with the string value ( or to write a specific handlers for the parser, if supported )

I did it by inheriting from str, making it serializable by anything which knows how to handle str. Just a couple of changes here and there to make it immutable

if you're interested, here comes a diff

diff --git a/txmongo/_pymongo/bson.py b/txmongo/_pymongo/bson.py
index aef08f8..7587ff1 100644
--- a/txmongo/_pymongo/bson.py
+++ b/txmongo/_pymongo/bson.py
@@ -416,6 +416,8 @@ def _element_to_bson(key, value, check_keys):
         full_length = struct.pack("<i", 8 + len(cstring) + len(scope))
         length = struct.pack("<i", len(cstring))
         return "\x0F" + name + full_length + length + cstring + scope
+    if isinstance(value, ObjectId):
+        return "\x07" + name + value.binary
     if isinstance(value, str):
         cstring = _make_c_string(value)
         length = struct.pack("<i", len(cstring))
@@ -429,8 +431,6 @@ def _element_to_bson(key, value, check_keys):
     if isinstance(value, (list, tuple)):
         as_dict = SON(zip([str(i) for i in range(len(value))], value))
         return "\x04" + name + _dict_to_bson(as_dict, check_keys)
-    if isinstance(value, ObjectId):
-        return "\x07" + name + value.binary
     if value is True:
         return "\x08" + name + "\x01"
     if value is False:
diff --git a/txmongo/_pymongo/objectid.py b/txmongo/_pymongo/objectid.py
index 1c8de98..4c43cea 100644
--- a/txmongo/_pymongo/objectid.py
+++ b/txmongo/_pymongo/objectid.py
@@ -41,7 +41,7 @@ def _machine_bytes():
     return machine_hash.digest()[0:3]


-class ObjectId(object):
+class ObjectId( str ):
     """A Mongo ObjectId.
     """

@@ -50,7 +50,7 @@ class ObjectId(object):

     _machine_bytes = _machine_bytes()

-    def __init__(self, oid=None):
+    def __new__(klass, oid=None):
         """Initialize a new ObjectId_.

         If `oid` is ``None``, create a new (unique)
@@ -70,11 +70,16 @@ class ObjectId(object):
         .. _ObjectId: http://www.mongodb.org/display/DOCS/Object+IDs
         """
         if oid is None:
-            self.__generate()
+            oid = klass._generate()
         else:
-            self.__validate(oid)
+            oid = klass._validate(oid)

-    def __generate(self):
+        self = str.__new__( klass, oid.encode("hex") )
+        self.__id = oid
+        return self
+
+    @classmethod
+    def _generate(klass):
         """Generate a new value for this ObjectId.
         """
         oid = ""
@@ -94,9 +99,10 @@ class ObjectId(object):
         ObjectId._inc = (ObjectId._inc + 1) % 0xFFFFFF
         ObjectId._inc_lock.release()

-        self.__id = oid
+        return oid

-    def __validate(self, oid):
+    @classmethod
+    def _validate(self, oid):
         """Validate and use the given id for this ObjectId.

         Raises TypeError if id is not an instance of (str, ObjectId) and
@@ -106,13 +112,13 @@ class ObjectId(object):
           - `oid`: a valid ObjectId
         """
         if isinstance(oid, ObjectId):
-            self.__id = oid.__id
+            return oid.__id
         elif isinstance(oid, basestring):
             if len(oid) == 12:
-                self.__id = oid
+                return oid
             elif len(oid) == 24:
                 try:
-                    self.__id = oid.decode("hex")
+                    return oid.decode("hex")
                 except TypeError:
                     raise InvalidId("%s is not a valid ObjectId" % oid)
             else:
@@ -154,9 +160,6 @@ class ObjectId(object):
         return datetime.datetime.utcfromtimestamp(t)
     generation_time = property(generation_time)

-    def __str__(self):
-        return self.__id.encode("hex")
-
     def __repr__(self):
         return "ObjectId('%s')" % self.__id.encode("hex")

[fiorix]

Oh yes, I had the same issue a while ago. Have you seen the solution for this on the original pymongo driver?
Check this out: https://github.com/mongodb/mongo-python-driver/blob/master/bson/json_util.py
I'd like to make it a simple string, but I also like the idea of keeping this driver in sync with the original driver.. I just don't have enough time to dedicate to it.

[doncatnip]

I didn't seen the pymongo solution. I agree, it's nice to keep stuff in sync - however, i needed a solution which would work with other serializers too, like cjson.

[fiorix]

Sure, I agree it's better if it works on other json serializers. Not sure what to do... Will come back (soon?) with more on this...

[doncatnip]

I'll try to bring this to the pymongo folks (soon?), as i just now realize that this is the very _pymongo package ( was kinda tired yesterday ) ...

[fiorix]

Perfect!