[PonyORM-list] Pony ORM Release 0.5.3

Alexey Malashkevich alexeymalashkevich at gmail.com
Tue Aug 12 14:09:45 UTC 2014

Hi all,

Pony ORM Release 0.5.3 is out!

This release includes preliminary changes required for Python 3 support,
fixes using lambdas in query filters and adds the new entity instance
method 'to_dict()':

to_dict(only=None, exclude=None, with_collections=False, with_lazy=False,

Returns a dictionary with attribute names and its values. This method can
be used when you need to serialize an object to JSON or other format.

By default this method doesn’t include collections (relationships to-many)
and lazy attributes. If an attribute’s values is an entity instance then
only the primary key of this object will be added to the dictionary.

only – use this parameter if you want to get only the specified attributes.
This argument can be used as a first positional argument. You can specify a
list of attribute names obj.to_dict(['id', 'name']), a string separated by
spaces: obj.to_dict('id name'), or a string separated by spaces with
commas: obj.to_dict('id, name').

exclude – this parameter allows to exclude specified attributes. Attribute
names can be specified the same way as for the only parameter.

related_objects – by default, all related objects represented as a primary
key. If related_objects=True, then objects which have relationships with
the current object will be added to the resulting dict as objects, not
their primary keys. It can be useful if you want to walk the related
objects and call the to_dict() method recursively.

with_collectionsTrue, then the relationships to-many will be represented as
lists. If related_objects=False (which is by default), then those lists
will consist of primary keys of related instances. If related_objects=True
then to-many collections will be represented as lists of objects.

with_lazy – if True, then lazy attributes (such as BLOBs or attributes
which are declared with lazy=True) will be included to the resulting dict.

For illustrating the usage of this method we will use the eStore example
which comes with Pony distribution. Let’s get a customer object with the
id=1 and convert it to a dictionary:

       >>> from pony.orm.examples.estore import *
       >>> c1 = Customer[1]
       >>> c1.to_dict()

       {'address': u'address 1',
       'country': u'USA',
       'email': u'john at example.com',
       'id': 1,
       'name': u'John Smith',
       'password': u'***'}

If we don’t want to serialize the password attribute, we can exclude it
this way:

       >>> c1.to_dict(exclude='password')

       {'address': u'address 1',
       'country': u'USA',
       'email': u'john at example.com',
       'id': 1,
       'name': u'John Smith'}

If you want to exclude more than one attribute, you can specify them as a
list: exclude=['id', 'password'] or as a string: exclude='id, password'
which is the same as exclude='id password'.

Also you can specify only the attributes, which you want to serialize using
the parameter only:

       >>> c1.to_dict(only=['id', 'name'])

       {'id': 1, 'name': u'John Smith'}

       >>> c1.to_dict('name email') # 'only' parameter as a positional

       {'email': u'john at example.com', 'name': u'John Smith'}

By default the collections are not included to the resulting dict. If you
want to include them, you can specify with_collections=True. Also you can
specify the collection attribute in the only parameter:

       >>> c1.to_dict(with_collections=True)

      {'address': u'address 1',
       'cart_items': [1, 2],
       'country': u'USA',
       'email': u'john at example.com',
       'id': 1,
       'name': u'John Smith',
       'orders': [1, 2],
       'password': u'***'}

By default all related objects (cart_items, orders) are represented as a
list with their primary keys. If you want to see the related objects
instances, you can specify related_objects=True:

       >>> c1.to_dict(with_collections=True, related_objects=True)

       {'address': u'address 1',
       'cart_items': [CartItem[1], CartItem[2]],
       'country': u'USA',
       'email': u'john at example.com',
       'id': 1,
       'name': u'John Smith',
       'orders': [Order[1], Order[2]],
       'password': u'***'}

P.S. Also the this release fixes the Release 0.5.2 which had problems with
the setup.py file.

Pony ORM Team
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