4c9e90732e
If a field has a default, and you explicitly set it to None, the
behaviour before this patch was very confusing:
class Person(Document):
created = DateTimeField(default=datetime.datetime.utcnow)
>>> p = Person(created=None)
>>> p.created
datetime.datetime(2013, 5, 30, 0, 18, 20, 242628)
>>> p.created
datetime.datetime(2013, 5, 30, 0, 18, 20, 995248)
>>> p.created
datetime.datetime(2013, 5, 30, 0, 18, 21, 370578)
It would be stored as None, and then at 'get' time, the default would be
applied. As you can see, if the default is a generator, this leads to some
crazy behaviour.
There's an argument that if I asked it to be set to None, why not respect that?
But I don't think that's how the rest of mongoengine seems to work (for
example, setting a field to None seems to mean it doesn't even get set in mongo
- as opposed to being set but with a 'null' value). Besides, as the code shows
above, you'd expect p.created to return None. So clearly, mongoengine is
already expecting None to mean 'default' where a default is available.
This bug also interacts nastily with required=True - if you're forcibly setting
the field to None, then at validation time, the None will fail validation
despite a perfectly valid default being available.
With this patch, when the field is set, the default is immediately applied.
This means any generation happens once, the getter always returns the same
value, and 'required' validation always respects the default.
Note: this breakage seems to be new since mongoengine 0.8.
===========
MongoEngine
===========
:Info: MongoEngine is an ORM-like layer on top of PyMongo.
:Repository: https://github.com/MongoEngine/mongoengine
:Author: Harry Marr (http://github.com/hmarr)
:Maintainer: Ross Lawley (http://github.com/rozza)
.. image:: https://secure.travis-ci.org/MongoEngine/mongoengine.png?branch=master
:target: http://travis-ci.org/MongoEngine/mongoengine
About
=====
MongoEngine is a Python Object-Document Mapper for working with MongoDB.
Documentation available at http://mongoengine-odm.rtfd.org - there is currently
a `tutorial <http://readthedocs.org/docs/mongoengine-odm/en/latest/tutorial.html>`_, a `user guide
<https://mongoengine-odm.readthedocs.org/en/latest/guide/index.html>`_ and an `API reference
<http://readthedocs.org/docs/mongoengine-odm/en/latest/apireference.html>`_.
Installation
============
If you have `setuptools <http://peak.telecommunity.com/DevCenter/setuptools>`_
you can use ``easy_install -U mongoengine``. Otherwise, you can download the
source from `GitHub <http://github.com/MongoEngine/mongoengine>`_ and run ``python
setup.py install``.
Dependencies
============
- pymongo 2.5+
- sphinx (optional - for documentation generation)
Examples
========
Some simple examples of what MongoEngine code looks like::
class BlogPost(Document):
title = StringField(required=True, max_length=200)
posted = DateTimeField(default=datetime.datetime.now)
tags = ListField(StringField(max_length=50))
class TextPost(BlogPost):
content = StringField(required=True)
class LinkPost(BlogPost):
url = StringField(required=True)
# Create a text-based post
>>> post1 = TextPost(title='Using MongoEngine', content='See the tutorial')
>>> post1.tags = ['mongodb', 'mongoengine']
>>> post1.save()
# Create a link-based post
>>> post2 = LinkPost(title='MongoEngine Docs', url='hmarr.com/mongoengine')
>>> post2.tags = ['mongoengine', 'documentation']
>>> post2.save()
# Iterate over all posts using the BlogPost superclass
>>> for post in BlogPost.objects:
... print '===', post.title, '==='
... if isinstance(post, TextPost):
... print post.content
... elif isinstance(post, LinkPost):
... print 'Link:', post.url
... print
...
>>> len(BlogPost.objects)
2
>>> len(HtmlPost.objects)
1
>>> len(LinkPost.objects)
1
# Find tagged posts
>>> len(BlogPost.objects(tags='mongoengine'))
2
>>> len(BlogPost.objects(tags='mongodb'))
1
Tests
=====
To run the test suite, ensure you are running a local instance of MongoDB on
the standard port, and run: ``python setup.py test``.
Community
=========
- `MongoEngine Users mailing list
<http://groups.google.com/group/mongoengine-users>`_
- `MongoEngine Developers mailing list
<http://groups.google.com/group/mongoengine-dev>`_
- `#mongoengine IRC channel <http://webchat.freenode.net/?channels=mongoengine>`_
Contributing
============
We welcome contributions! see the`Contribution guidelines <https://github.com/MongoEngine/mongoengine/blob/master/CONTRIBUTING.rst>`_