Updated ReferenceField's to optionally store ObjectId strings.

This will become the default in 0.8 (MongoEngine/mongoengine#89)

docs/changelog.rst

@@ -4,6 +4,9 @@ Changelog
 
 Changes in 0.7.X
 =================
+
+- Updated ReferenceField's to optionally store ObjectId strings
+  this will become the default in 0.8 (MongoEngine/mongoengine#89)
 - Added FutureWarning - save will default to `cascade=False` in 0.8
 - Added example of indexing embedded document fields (MongoEngine/mongoengine#75)
 - Fixed ImageField resizing when forcing size (MongoEngine/mongoengine#80)

docs/upgrade.rst

@@ -5,9 +5,13 @@ Upgrading
 0.6 to 0.7
 ==========
 
-Saves will raise a `FutureWarning` if they cascade and cascade hasn't been set to
-True.  This is because in 0.8 it will default to False.  If you require cascading
-saves then either set it in the `meta` or pass via `save` ::
+Cascade saves
+-------------
+
+Saves will raise a `FutureWarning` if they cascade and cascade hasn't been set
+to True.  This is because in 0.8 it will default to False.  If you require
+cascading saves then either set it in the `meta` or pass
+via `save` eg ::
 
     # At the class level:
     class Person(Document):
@@ -16,18 +20,52 @@ saves then either set it in the `meta` or pass via `save` ::
     # Or in code:
     my_document.save(cascade=True)
 
+.. note ::
+    Remember: cascading saves **do not** cascade through lists.
+
+ReferenceFields
+---------------
+
+ReferenceFields now can store references as ObjectId strings instead of DBRefs.
+This will become the default in 0.8 and if `dbref` is not set a `FutureWarning`
+will be raised.
+
+
+To explicitly continue to use DBRefs change the `dbref` flag
+to True ::
+
+   class Person(Document):
+       groups = ListField(ReferenceField(Group, dbref=True))
+
+To migrate to using strings instead of DBRefs you will have to manually
+migrate ::
+
+        # Step 1 - Migrate the model definition
+        class Group(Document):
+            author = ReferenceField(User, dbref=False)
+            members = ListField(ReferenceField(User, dbref=False))
+
+        # Step 2 - Migrate the data
+        for g in Group.objects():
+            g.author = g.author
+            g.members = g.members
+            g.save()
+
+
 0.5 to 0.6
 ==========
 
-Embedded Documents - if you had a `pk` field you will have to rename it from `_id`
-to `pk` as pk is no longer a property of Embedded Documents.
+Embedded Documents - if you had a `pk` field you will have to rename it from
+`_id` to `pk` as pk is no longer a property of Embedded Documents.
 
 Reverse Delete Rules in Embedded Documents, MapFields and DictFields now throw
 an InvalidDocument error as they aren't currently supported.
 
-Document._get_subclasses - Is no longer used and the class method has been removed.
+Document._get_subclasses - Is no longer used and the class method has been
+removed.
 
-Document.objects.with_id - now raises an InvalidQueryError if used with a filter.
+Document.objects.with_id - now raises an InvalidQueryError if used with a
+filter.
 
 FutureWarning - A future warning has been added to all inherited classes that
 don't define `allow_inheritance` in their meta.
@@ -51,11 +89,11 @@ human-readable name for the option.
 PyMongo / MongoDB
 -----------------
 
-map reduce now requires pymongo 1.11+- The pymongo merge_output and reduce_output
-parameters, have been depreciated.
+map reduce now requires pymongo 1.11+- The pymongo `merge_output` and
+`reduce_output` parameters, have been depreciated.
 
-More methods now use map_reduce as db.eval is not supported for sharding as such
-the following have been changed:
+More methods now use map_reduce as db.eval is not supported for sharding as
+such the following have been changed:
 
     * :meth:`~mongoengine.queryset.QuerySet.sum`
     * :meth:`~mongoengine.queryset.QuerySet.average`
@@ -65,8 +103,8 @@ the following have been changed:
 Default collection naming
 -------------------------
 
-Previously it was just lowercase, its now much more pythonic and readable as its
-lowercase and underscores, previously ::
+Previously it was just lowercase, its now much more pythonic and readable as
+its lowercase and underscores, previously ::
 
     class MyAceDocument(Document):
         pass
@@ -102,7 +140,8 @@ Alternatively, you can rename your collections eg ::
 
         failure = False
 
-        collection_names = [d._get_collection_name() for d in _document_registry.values()]
+        collection_names = [d._get_collection_name()
+                            for d in _document_registry.values()]
 
         for new_style_name in collection_names:
             if not new_style_name:  # embedded documents don't have collections
@@ -120,7 +159,8 @@ Alternatively, you can rename your collections eg ::
                         old_style_name, new_style_name)
                 else:
                     db[old_style_name].rename(new_style_name)
-                    print "Renamed:  %s to %s" % (old_style_name, new_style_name)
+                    print "Renamed:  %s to %s" % (old_style_name,
+                                                  new_style_name)
 
         if failure:
             print "Upgrading  collection names failed"