Upgrading

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.

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.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.

You may need to update pyMongo to 2.0 for use with Sharding.

0.4 to 0.5

There have been the following backwards incompatibilities from 0.4 to 0.5. The main areas of changed are: choices in fields, map_reduce and collection names.

Choice options:

Are now expected to be an iterable of tuples, with the first element in each tuple being the actual value to be stored. The second element is the 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.

More methods now use map_reduce as db.eval is not supported for sharding as such the following have been changed:

• sum()
• average()
• item_frequencies()

Default collection naming

Previously it was just lowercase, its now much more pythonic and readable as its lowercase and underscores, previously

class MyAceDocument(Document):
    pass

MyAceDocument._meta['collection'] == myacedocument

In 0.5 this will change to

class MyAceDocument(Document):
    pass

MyAceDocument._get_collection_name() == my_ace_document

To upgrade use a Mixin class to set meta like so

class BaseMixin(object):
    meta = {
        'collection': lambda c: c.__name__.lower()
    }

class MyAceDocument(Document, BaseMixin):
    pass

MyAceDocument._get_collection_name() == "myacedocument"

Alternatively, you can rename your collections eg

from mongoengine.connection import _get_db
from mongoengine.base import _document_registry

def rename_collections():
    db = _get_db()

    failure = False

    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
            continue
        old_style_name = new_style_name.replace('_', '')

        if old_style_name == new_style_name:
            continue  # Nothing to do

        existing = db.collection_names()
        if old_style_name in existing:
            if new_style_name in existing:
                failure = True
                print "FAILED to rename: %s to %s (already exists)" % (
                    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)

    if failure:
        print "Upgrading  collection names failed"
    else:
        print "Upgraded collection names"