Entities

Entities is a Python library for automated object validation and serialization. It is useful in cases where you need well-defined entity models but you don't specifically need a storage backend or a form validator. It supports recursive and non-recursive collection types (list, set and dict), nested entities and reference fields. It can automatically validate, serialize, deserialize and generate hashable keys for entities of any complexity.

Installation

You can install the most recent release using pip:

pip install entities

Usage

Typical usage looks like this:

from entities import *

class Account(Entity):
    id = IntegerField(group=PRIMARY)  # this field is in primary key group
    iban = IntegerField(group=SECONDARY)  # this is in secondary key group
    balance = FloatField(default=0.0)

class Name(Entity):
    first_name = StringField(group=SECONDARY)
    last_name = StringField(group=SECONDARY)

class Customer(Entity):
    id = IntegerField(group=PRIMARY)
    name = EntityField(Name, group=SECONDARY)
    accounts = ListField(ReferenceField(Account), default=list)

# Create Account objects.
a_1 = Account(1, 111, 10.0)  # __init__() recognizes positional arguments
a_2 = Account(id=2, iban=222, balance=20.0)  # as well as keyword arguments

# Generate hashable key using primary key.
print a_1.keyify()  # prints '(1,)'

# Generate hashable key using secondary key.
print a_2.keyify(SECONDARY)  # prints '(222,)'

# Create Customer object.
c = Customer(1, Name('eser', 'aygun'))

# Generate hashable key using primary key.
print c.keyify()  # prints '(1,)'

# Generate hashable key using secondary key.
print c.keyify(SECONDARY)  # prints '(('eser', 'aygun'),)'

# Try validating an invalid object.
c.accounts.append(123)
try:
    c.validate()  # fails
except ValidationError:
    print 'accounts list is only for Account objects'

# Try validating a valid object.
c.accounts = [a_1, a_2]
c.validate()  # succeeds

TODO List

• JSON serialization module (should be pretty easy)
• BSON serialization module (for MongoDB compatibility)