MedeaMapper¶

A mapper conviniently maps attributes between a Python and a JSON object. It is callable and can be registered with medea directly.

class Pet(object):
    pass


class Dog(Pet):
    def __init__(self, name):
        self.name = name
        self.kind = 'Dog'


class Cat(Pet):
    def __init__(self, name):
        self.name = name
        self.kind = 'Cat'


class PetPerson(Person):
    pass


medea.register(PetPerson, MedeaCamelMapper('first_name', 'last_name', 'pets'))
medea.register(Pet, MedeaCamelMapper('name', 'kind'))

anne = PetPerson('Anne', 'Frank')
fido = Dog('Fido')
spot = Dog('Spot')
garfield = Cat('Garfield')
anne.pets = [fido, spot, garfield]
assert medea(anne) == {
    'firstName': 'Anne',
    'lastName': 'Frank',
    'pets': [
        {'kind': 'Dog', 'name': 'Fido'},
        {'kind': 'Dog', 'name': 'Spot'},
        {'kind': 'Cat', 'name': 'Garfield'}]}

Create a mapper using Python attribute names as arguments. Attributes that are not whitelisted will not be serialized:

class Person(object):
    def __init__(self, first_name, last_name,
                 address='', phone_number='', dob=''):
        self.first_name = first_name
        self.last_name = last_name
        self.address = address
        self.phone_number = phone_number
        self.dob = dob


bob = Person('Bob', 'Hope', '123 Main', '123', '1903-05-29')

mapper = MedeaMapper('first_name', 'last_name',
                     'address', 'phone_number', 'dob')

bob_json = {
    'first_name': 'Bob',
    'last_name': 'Hope',
    'address': '123 Main',
    'phone_number': '123',
    'dob': '1903-05-29'}

assert mapper.to_json(bob) == bob_json

Attribute names can be overridden using **kwargs.

bob = Person('Bob', 'Hope', '123 Main', '123', '1903-05-29')

mapper = MedeaMapper('address', 'dob',
                     first_name='firstName', last_name='lastName')

bob_json = {
    'firstName': 'Bob',
    'lastName': 'Hope',
    'address': '123 Main',
    'dob': '1903-05-29'}

assert mapper.to_json(bob) == bob_json

MedeaCamelMapper may be useful if JSON is camel cased.

bob = Person('Bob', 'Hope', '123 Main', '123', '1903-05-29')

mapper = MedeaCamelMapper('first_name', 'last_name',
                          'address', 'phone_number', 'dob')

bob_json = {
    'firstName': 'Bob',
    'lastName': 'Hope',
    'address': '123 Main',
    'phoneNumber': '123',
    'dob': '1903-05-29'}

assert mapper.to_json(bob) == bob_json

A mapper can also map attribues from JSON onto the object:

bob = Person('Bob', 'Hope', '123 Main', '123', '1903-05-29')

bob_json_full = {
    'firstName': 'Bob',
    'lastName': 'Hope',
    'address': '123 Main',
    'phoneNumber': '123',
    'DOB': '1903-05-29'}

fred_json = {
    'firstName': 'Fred',
    'lastName': 'Rodgers'}

mapper = MedeaCamelMapper('first_name', 'last_name')
mapper_full = MedeaCamelMapper('first_name', 'last_name',
                               'address', 'phone_number', dob='DOB')

assert mapper.to_json(bob) == bob_json
assert mapper_full.to_json(bob) == bob_json_full

# Override Bob's name from Fred
mapper.from_json(fred_json, bob)

# Mapper only serializes names
assert mapper.to_json(bob) == fred_json
assert mapper_full.to_json(bob) != bob_json_full
assert bob.first_name == 'Fred'
assert bob.last_name == 'Rodgers'
assert bob.address == '123 Main'
assert bob.phone_number == '123'
assert bob.dob == '1903-05-29'

# Revert back to Bob's name
mapper.from_json(bob_json, bob)
assert mapper.to_json(bob) == bob_json
assert mapper_full.to_json(bob) == bob_json_full