models.py

import logging
from copy import deepcopy
from bravado_core.marshal import marshal_schema_object
from bravado_core.unmarshal import unmarshal_model
import bravado_core.model
from pymacaron_core.exceptions import ValidationError
from pymacaron_core.utils import get_function


log = logging.getLogger(__name__)


class Models():
    """Class holding all generated models"""
    pass


def get_model(model_name):
    if hasattr(Models, model_name):
        return getattr(Models, model_name)
    raise ValidationError("Swagger spec has no definition for model %s" % model_name)


class PyMacaronModel(object):
    """Instances of PyMacaron Model are passed to and returned by the API
    endpoints.

    They encapsulate an instance of a Bravado model that holds the instance's
    attributes, they may inherit from a parent class, they can be serialized to
    and from json, they can be loaded from and to a persistent database.

    """

    # Class variables: Name of this model and pymacaron-core ApiSpec of that model
    __model_name = None
    __swagger_dict = None
    __swagger_spec = None

    #
    # Delegate getter/setter/etc to Bravado model
    #

    def __setattr__(self, k, v):
        if k in getattr(self, '__property_names'):
            setattr(getattr(self, '__bravado_instance'), k, v)
        else:
            super().__setattr__(k, v)


    def __getattr__(self, k):
        # NOTE: overriding __getattr__ is tricky since we need __property_names early,
        # and getattr() is used by hasattr() to check if an attribute exists
        if k.endswith('__property_names'):
            return getattr(self, '__property_names')
        elif k in getattr(self, '__property_names'):
            return getattr(getattr(self, '__bravado_instance'), k)
        elif k not in dir(self):
            raise AttributeError("Model '%s' has no attribute %s" % (getattr(self, '__model_name'), k))
        else:
            return getattr(self, k)


    def __delattr__(self, k):
        if k in getattr(self, '__property_names'):
            delattr(getattr(self, '__bravado_instance'), k)
        else:
            super().__delattr__(k)


    def __getitem__(self, k):
        if k not in getattr(self, '__property_names'):
            raise AttributeError("Model '%s' has no attribute %s" % (getattr(self, '__model_name'), k))
        return getattr(getattr(self, '__bravado_instance'), k)


    def __setitem__(self, k, v):
        if k not in getattr(self, '__property_names'):
            raise AttributeError("Model '%s' has no attribute %s" % (getattr(self, '__model_name'), k))
        setattr(getattr(self, '__bravado_instance'), k, v)


    def __delitem__(self, k):
        if k not in getattr(self, '__property_names'):
            raise AttributeError("Model '%s' has no attribute %s" % (getattr(self, '__model_name'), k))
        delattr(getattr(self, '__bravado_instance'), k)


    def __eq__(self, other):
        if type(self) is not type(other):
            return False
        return getattr(self, '__bravado_instance') == getattr(other, '__bravado_instance')


    def __repr__(self):
        return 'PyMacaron:%s:%s' % (getattr(self, '__model_name'), str(getattr(self, '__bravado_instance')))


    #
    # Convenience methods
    #


    def update_from_dict(self, d, ignore_none=False):
        """Take a dictionary of key-values representing attribute and values to update
        in the encapsulated Bravado instance. Note that setting an attribute to
        None actually means removing it from the model instance, and thereby
        from its json representation, except if ignore_none is True, in which case
        the attribute is kept unchanged.
        """

        for k, v in d.items():
            if v is None and ignore_none:
                pass
            elif v is None:
                delattr(getattr(self, '__bravado_instance'), k)
            else:
                setattr(getattr(self, '__bravado_instance'), k, v)


    def clone(self):
        """Return a clone of self"""
        j = self.to_json()
        return self.__class__.from_json(j)

    #
    # JSON marshal/unmarshal
    #


    def to_json(self, keep_datetime=False):
        """Return a json representation of this PyMacaron object - If keep_datetime is set,
        will keep attributes that are datetime unchanged.
        """
        log.debug("Marshalling %s into json" % getattr(self, '__model_name'))
        datetimes = {}
        if keep_datetime:
            for k in self.__property_names:
                if hasattr(self, k) and getattr(self, k).__class__.__name__ in ('datetime', 'DatetimeWithNanoseconds'):
                    datetimes[k] = getattr(self, k)
        j = marshal_schema_object(
            getattr(self, '__swagger_spec'),
            getattr(self, '__swagger_dict'),
            self.to_bravado(),
        )
        if datetimes:
            j.update(datetimes)
        return j


    @classmethod
    def from_json(cls, j, keep_datetime=False):
        """Take a json dictionary and return a model instance"""
        log.debug("Unmarshalling json into %s" % getattr(cls, '__model_name'))
        datetimes = {}
        if keep_datetime:
            for k in list(j.keys()):
                if j[k].__class__.__name__ in ('datetime', 'DatetimeWithNanoseconds'):
                    datetimes[k] = j[k]
                    del j[k]

        m = unmarshal_model(
            getattr(cls, '__swagger_spec'),
            getattr(cls, '__swagger_dict'),
            j
        )

        if datetimes:
            for k in datetimes:
                setattr(m, k, datetimes[k])

        return cls.from_bravado(m)


    def get_model_name(self):
        """Return the name of the OpenAPI schema object describing this PyMacaron Model instance"""
        return getattr(self, '__model_name')

    #
    # Methods to cast a PyMacaron Model to/from a Bravado Model
    #

    def to_bravado(self):
        """Return a pure Bravado Model representing self"""

        # Get internal Bravado instance and clone it
        o = getattr(self, '__bravado_instance')
        o = deepcopy(o)

        # Do the same recursively with every nested PyMacaron Model
        for k in getattr(self, '__property_names'):
            v = getattr(o, k)
            if isinstance(v, PyMacaronModel):
                setattr(o, k, v.to_bravado())
            elif type(v) is list:
                for i in range(len(v)):
                    if isinstance(v[i], PyMacaronModel):
                        v[i] = v[i].to_bravado()
        return o


    @classmethod
    def from_bravado(cls, o):
        """Take a bravado Model instance and return a PyMacaron Model instance"""

        # Clone bravado instance and inject it into a matching PyMacaron model instance
        o = deepcopy(o)
        p = cls()
        setattr(p, '__bravado_instance', o)

        # Now cast from bravado to pymacaron models all the attributes of this model
        for k in getattr(p, '__property_names'):
            v = getattr(o, k)
            if isinstance(v, bravado_core.model.Model):
                cls = get_model(v.__class__.__name__)
                setattr(o, k, cls.from_bravado(v))
            elif type(v) is list:
                for i in range(len(v)):
                    if isinstance(v[i], bravado_core.model.Model):
                        cls = get_model(v[i].__class__.__name__)
                        v[i] = cls.from_bravado(v[i])
        return p


def generate_model_class(name=None, bravado_class=None, swagger_dict=None, swagger_spec=None, parent_name=None, persist=None, properties={}):
    """Dynamically generate a pymacaron.models.<model_name> class able to
    instantiate that model.

    :name: the model name, as in the swagger spec
    :parent_name: complete name (module path + class name) of a class that this model should inherit from.
    :param persist: name of a package or class that implements the 'load_from_db' and 'save_to_db' methods.
    """

    if parent_name:
        assert type(parent_name) is str

    if persist:
        assert type(persist) is str

    # Which parents are we inheriting?
    parents = (PyMacaronModel, )
    if parent_name:
        parent_class = get_function(parent_name)
        parents = parents + (parent_class, )

    # Is this model persistent?
    persistence_class = None
    if persist:
        persistence_class = get_function(persist)
        parents = parents + (persistence_class, )

    # Generate the instance's constructor
    def init(self, *args, **kwargs):
        self.__bravado_instance = bravado_class(*args, **kwargs)

    # And generate the model's class
    o = type(
        name,
        parents,
        {
            '__init__': init,
            '__model_name': name,
            '__persistence_class__': persist,
            '__property_names': list(properties.keys()),
            '__swagger_spec': swagger_spec,
            '__swagger_dict': swagger_dict,
        },
    )

    # And remember the mapping between this bravado model and its pymacaron model
    setattr(Models, name, o)

    return o