Simple types and inheritance

Let us define a very basic Person type that defines two string fields:

class Person(SerialObject):
    __fields__ = {
        'name': str,
        'job': str
    }

Now we can simply deserialize json-compatible data to it, and/or serialize its instances to a json-like structure:

>>> person_data = {
...     'name': 'Bob',
...     'job': 'lumberjack'
... }
>>> bob = Person.deserialize(person_data)
>>> bob.name
'Bob'
>>> bob.job
'lumberjack'
>>> bob.serialize()
{'job': 'lumberjack', 'name': 'Bob'}

Of course there is more to it than that. Let us subclass our Person, to define, for instance a TeamMate, which overrides the job field to allow it to be a dict and to add a new str field: role.

class TeamMate(Person):
    __fields__ = {
        'role': str,
        'job': dict
    }

Of course this is a silly example, but this allows us to demonstrate that inheriting a SerialObject class allows to inherit, override and specialize the structure definition :

>>> bob2 = TeamMate.deserialize(teammate_data)
>>> bob2.name
'Bob'
>>> bob2.job
{'all night': 'sleep', 'all day': 'work'}
>>> bob2.serialize()
{'role': 'lumberjack', 'name': 'Bob', 'job': {'all night': 'sleep', 'all day': 'work'}}

It also allows us to demonstrate that the structure is actually checked against the model: let’s try and deserialize our teammate_data with the incompatible Person model.

>>> Person.deserialize(teammate_data)
Traceback (most recent call last):
  File "<input>", line 1, in <module>
    Person.deserialize(teammate_data)
  File "/home/arnaud/work/serialobj/serialobj.py", line 242, in deserialize
    for key, val in data.items() if key in cls.__fields__
  File "/home/arnaud/work/serialobj/serialobj.py", line 242, in <dictcomp>
    for key, val in data.items() if key in cls.__fields__
  File "/home/arnaud/work/serialobj/serialobj.py", line 86, in deserialize
    .format(self.cls_.__name__, data))
serialobj.InvalidTypeError: Expected str, got {'all night': 'sleep', 'all day': 'work'}

Isn’t it starting to get interesting?

List of objects

Let us spice it up a little bit. What if I want to define a field as a list of strings?

Well, there is some sugar for this:

class Task(SerialObject):
    __fields__ = {
        'title': str,
        'description': str,
        'checklist': [str]
    }

See for yourself:

>>> data = {
...     'title': 'timber some wood',
...     'description': '',
...     'checklist': [
...         'some wood is timbered',
...         'the lumberjack is okay',
...         'he sleeps all night and works all day'
...     ]
... }
>>> tsk = Task.deserialize(data)
>>> tsk.checklist
['some wood is timbered', 'the lumberjack is okay', 'he sleeps all night and works all day']
>>> tsk.checklist.append("... and that's it")
>>> pprint(tsk.serialize())
{'checklist': ['some wood is timbered',
               'the lumberjack is okay',
               'he sleeps all night and works all day',
               "... and that's it"],
 'description': '',
 'title': 'timber some wood'}

Going fancy

Of course, all these are the base building blocks to define arbitrarily complex JSON-API structures:

class Team(SerialObject):
    __fields__ = {
        'name': str,
        'manager': TeamMate,
        'members': [TeamMate],
        'backlog': [Task]
    }


COMPLEX_DATA = {
    'name': "The good ol' lumberjacks",
    'manager': {
        'name': 'Bob',
        'role': 'Be okay'
    },
    'members': [
        {
            'name': 'Jack',
            'role': 'sleep all night'
        },
        {
            'name': 'Barry',
            'role': 'work all day',
        }],
    'backlog': [
        {
            'title': 'timber some wood',
            'description': '',
            'checklist': [
                'some wood is timbered',
                'the lumberjack is okay',
                'he sleeps all night and works all day'
            ]
        }]
    }

Here we go:

>>> team = Team.deserialize(COMPLEX_DATA)
>>> team.manager.name
'Bob'
>>> team.manager
<__console__.TeamMate object at 0x7f34edd2c9a8>
>>> team.backlog[0]
<__console__.Task object at 0x7f34edd9b7c8>
>>> team.backlog[0].title
'timber some wood'
>>> pprint(team.serialize())
{'backlog': [{'checklist': ['some wood is timbered',
                            'the lumberjack is okay',
                            'he sleeps all night and works all day'],
              'description': '',
              'title': 'timber some wood'}],
 'manager': {'name': 'Bob', 'role': 'Be okay'},
 'members': [{'name': 'Jack', 'role': 'sleep all night'},
             {'name': 'Barry', 'role': 'work all day'}],
 'name': "The good ol' lumberjacks"}