# -*- coding: utf-8 -*-
# Copyright: See the LICENSE file.
from __future__ import unicode_literals
import itertools
import logging
from . import enums
from . import compat
from . import errors
from . import utils
logger = logging.getLogger('factory.generate')
class BaseDeclaration(utils.OrderedBase):
"""A factory declaration.
Declarations mark an attribute as needing lazy evaluation.
This allows them to refer to attributes defined by other BaseDeclarations
in the same factory.
"""
def evaluate(self, instance, step, extra):
"""Evaluate this declaration.
Args:
instance (builder.Resolver): The object holding currently computed
attributes
step: a factory.builder.BuildStep
extra (dict): additional, call-time added kwargs
for the step.
"""
raise NotImplementedError('This is an abstract method')
class OrderedDeclaration(BaseDeclaration):
"""Compatibility"""
# FIXME(rbarrois)
[docs]class LazyFunction(BaseDeclaration):
"""Simplest BaseDeclaration computed by calling the given function.
Attributes:
function (function): a function without arguments and
returning the computed value.
"""
def __init__(self, function, *args, **kwargs):
super(LazyFunction, self).__init__(*args, **kwargs)
self.function = function
def evaluate(self, instance, step, extra):
logger.debug("LazyFunction: Evaluating %s on %s", utils.log_repr(self.function), utils.log_repr(step))
return self.function()
[docs]class LazyAttribute(BaseDeclaration):
"""Specific BaseDeclaration computed using a lambda.
Attributes:
function (function): a function, expecting the current LazyStub and
returning the computed value.
"""
def __init__(self, function, *args, **kwargs):
super(LazyAttribute, self).__init__(*args, **kwargs)
self.function = function
def evaluate(self, instance, step, extra):
logger.debug("LazyAttribute: Evaluating %s on %s", utils.log_repr(self.function), utils.log_repr(instance))
return self.function(instance)
class _UNSPECIFIED(object):
pass
def deepgetattr(obj, name, default=_UNSPECIFIED):
"""Try to retrieve the given attribute of an object, digging on '.'.
This is an extended getattr, digging deeper if '.' is found.
Args:
obj (object): the object of which an attribute should be read
name (str): the name of an attribute to look up.
default (object): the default value to use if the attribute wasn't found
Returns:
the attribute pointed to by 'name', splitting on '.'.
Raises:
AttributeError: if obj has no 'name' attribute.
"""
try:
if '.' in name:
attr, subname = name.split('.', 1)
return deepgetattr(getattr(obj, attr), subname, default)
else:
return getattr(obj, name)
except AttributeError:
if default is _UNSPECIFIED:
raise
else:
return default
[docs]class SelfAttribute(BaseDeclaration):
"""Specific BaseDeclaration copying values from other fields.
If the field name starts with two dots or more, the lookup will be anchored
in the related 'parent'.
Attributes:
depth (int): the number of steps to go up in the containers chain
attribute_name (str): the name of the attribute to copy.
default (object): the default value to use if the attribute doesn't
exist.
"""
def __init__(self, attribute_name, default=_UNSPECIFIED, *args, **kwargs):
super(SelfAttribute, self).__init__(*args, **kwargs)
depth = len(attribute_name) - len(attribute_name.lstrip('.'))
attribute_name = attribute_name[depth:]
self.depth = depth
self.attribute_name = attribute_name
self.default = default
def evaluate(self, instance, step, extra):
if self.depth > 1:
# Fetching from a parent
target = step.chain[self.depth - 1]
else:
target = instance
logger.debug("SelfAttribute: Picking attribute %r on %s", self.attribute_name, utils.log_repr(target))
return deepgetattr(target, self.attribute_name, self.default)
def __repr__(self):
return '<%s(%r, default=%r)>' % (
self.__class__.__name__,
self.attribute_name,
self.default,
)
[docs]class Iterator(BaseDeclaration):
"""Fill this value using the values returned by an iterator.
Warning: the iterator should not end !
Attributes:
iterator (iterable): the iterator whose value should be used.
getter (callable or None): a function to parse returned values
"""
def __init__(self, iterator, cycle=True, getter=None):
super(Iterator, self).__init__()
self.getter = getter
self.iterator = None
if cycle:
self.iterator_builder = lambda: utils.ResetableIterator(itertools.cycle(iterator))
else:
self.iterator_builder = lambda: utils.ResetableIterator(iterator)
def evaluate(self, instance, step, extra):
# Begin unrolling as late as possible.
# This helps with ResetableIterator(MyModel.objects.all())
if self.iterator is None:
self.iterator = self.iterator_builder()
logger.debug("Iterator: Fetching next value from %s", utils.log_repr(self.iterator))
value = next(iter(self.iterator))
if self.getter is None:
return value
return self.getter(value)
[docs] def reset(self):
"""Reset the internal iterator."""
self.iterator.reset()
[docs]class Sequence(BaseDeclaration):
"""Specific BaseDeclaration to use for 'sequenced' fields.
These fields are typically used to generate increasing unique values.
Attributes:
function (function): A function, expecting the current sequence counter
and returning the computed value.
type (function): A function converting an integer into the expected kind
of counter for the 'function' attribute.
"""
def __init__(self, function, type=int):
super(Sequence, self).__init__()
self.function = function
self.type = type
def evaluate(self, instance, step, extra):
logger.debug("Sequence: Computing next value of %r for seq=%s", self.function, step.sequence)
return self.function(self.type(step.sequence))
[docs]class LazyAttributeSequence(Sequence):
"""Composite of a LazyAttribute and a Sequence.
Attributes:
function (function): A function, expecting the current LazyStub and the
current sequence counter.
type (function): A function converting an integer into the expected kind
of counter for the 'function' attribute.
"""
def evaluate(self, instance, step, extra):
logger.debug(
"LazyAttributeSequence: Computing next value of %r for seq=%s, obj=%s",
self.function, step.sequence, utils.log_repr(instance))
return self.function(instance, self.type(step.sequence))
class ContainerAttribute(BaseDeclaration):
"""Variant of LazyAttribute, also receives the containers of the object.
Attributes:
function (function): A function, expecting the current LazyStub and the
(optional) object having a subfactory containing this attribute.
strict (bool): Whether evaluating should fail when the containers are
not passed in (i.e used outside a SubFactory).
"""
def __init__(self, function, strict=True, *args, **kwargs):
super(ContainerAttribute, self).__init__(*args, **kwargs)
self.function = function
self.strict = strict
def evaluate(self, instance, step, extra):
"""Evaluate the current ContainerAttribute.
Args:
obj (LazyStub): a lazy stub of the object being constructed, if
needed.
containers (list of LazyStub): a list of lazy stubs of factories
being evaluated in a chain, each item being a future field of
next one.
"""
# Strip the current instance from the chain
chain = step.chain[1:]
if self.strict and not chain:
raise TypeError(
"A ContainerAttribute in 'strict' mode can only be used "
"within a SubFactory.")
return self.function(instance, chain)
class ParameteredAttribute(BaseDeclaration):
"""Base class for attributes expecting parameters.
Attributes:
defaults (dict): Default values for the paramters.
May be overridden by call-time parameters.
Class attributes:
CONTAINERS_FIELD (str): name of the field, if any, where container
information (e.g for SubFactory) should be stored. If empty,
containers data isn't merged into generate() parameters.
"""
CONTAINERS_FIELD = '__containers'
# Whether to add the current object to the stack of containers
EXTEND_CONTAINERS = False
def __init__(self, **kwargs):
super(ParameteredAttribute, self).__init__()
self.defaults = kwargs
def _prepare_containers(self, obj, containers=()):
if self.EXTEND_CONTAINERS:
return (obj,) + tuple(containers)
return containers
def evaluate(self, instance, step, extra):
"""Evaluate the current definition and fill its attributes.
Uses attributes definition in the following order:
- values defined when defining the ParameteredAttribute
- additional values defined when instantiating the containing factory
Args:
instance (builder.Resolver): The object holding currently computed
attributes
step: a factory.builder.BuildStep
extra (dict): additional, call-time added kwargs
for the step.
"""
defaults = dict(self.defaults)
if extra:
defaults.update(extra)
return self.generate(step, defaults)
def generate(self, step, params):
"""Actually generate the related attribute.
Args:
sequence (int): the current sequence number
obj (LazyStub): the object being constructed
create (bool): whether the calling factory was in 'create' or
'build' mode
params (dict): parameters inherited from init and evaluation-time
overrides.
Returns:
Computed value for the current declaration.
"""
raise NotImplementedError()
class _FactoryWrapper(object):
"""Handle a 'factory' arg.
Such args can be either a Factory subclass, or a fully qualified import
path for that subclass (e.g 'myapp.factories.MyFactory').
"""
def __init__(self, factory_or_path):
self.factory = None
self.module = self.name = ''
if isinstance(factory_or_path, type):
self.factory = factory_or_path
else:
if not (compat.is_string(factory_or_path) and '.' in factory_or_path):
raise ValueError(
"A factory= argument must receive either a class "
"or the fully qualified path to a Factory subclass; got "
"%r instead." % factory_or_path)
self.module, self.name = factory_or_path.rsplit('.', 1)
def get(self):
if self.factory is None:
self.factory = utils.import_object(
self.module,
self.name,
)
return self.factory
def __repr__(self):
if self.factory is None:
return '<_FactoryImport: %s.%s>' % (self.module, self.name)
else:
return '<_FactoryImport: %s>' % self.factory.__class__
[docs]class SubFactory(ParameteredAttribute):
"""Base class for attributes based upon a sub-factory.
Attributes:
defaults (dict): Overrides to the defaults defined in the wrapped
factory
factory (base.Factory): the wrapped factory
"""
EXTEND_CONTAINERS = True
FORCE_SEQUENCE = False
def __init__(self, factory, **kwargs):
super(SubFactory, self).__init__(**kwargs)
self.factory_wrapper = _FactoryWrapper(factory)
def get_factory(self):
"""Retrieve the wrapped factory.Factory subclass."""
return self.factory_wrapper.get()
def generate(self, step, params):
"""Evaluate the current definition and fill its attributes.
Args:
step: a factory.builder.BuildStep
params (dict): additional, call-time added kwargs
for the step.
"""
subfactory = self.get_factory()
logger.debug(
"SubFactory: Instantiating %s.%s(%s), create=%r",
subfactory.__module__, subfactory.__name__,
utils.log_pprint(kwargs=params),
step,
)
force_sequence = step.sequence if self.FORCE_SEQUENCE else None
return step.recurse(subfactory, params, force_sequence=force_sequence)
[docs]class Dict(SubFactory):
"""Fill a dict with usual declarations."""
FORCE_SEQUENCE = True
def __init__(self, params, dict_factory='factory.DictFactory'):
super(Dict, self).__init__(dict_factory, **dict(params))
[docs]class List(SubFactory):
"""Fill a list with standard declarations."""
FORCE_SEQUENCE = True
def __init__(self, params, list_factory='factory.ListFactory'):
params = dict((str(i), v) for i, v in enumerate(params))
super(List, self).__init__(list_factory, **params)
# Parameters
# ==========
class Skip(object):
def __bool__(self):
return False
# Py2 compatibility
__nonzero__ = __bool__
SKIP = Skip()
[docs]class Maybe(BaseDeclaration):
def __init__(self, decider, yes_declaration=SKIP, no_declaration=SKIP):
self.decider = decider
self.yes = yes_declaration
self.no = no_declaration
def evaluate(self, instance, step, extra):
if isinstance(self.decider, BaseDeclaration):
choice = self.decider.evaluate(instance=instance, step=step, extra={})
else:
choice = getattr(instance, self.decider, None)
target = self.yes if choice else self.no
if isinstance(target, BaseDeclaration):
return target.evaluate(
instance=instance,
step=step,
extra=extra,
)
else:
# Flat value
return target
def __repr__(self):
return 'Maybe(%r, yes=%r, no=%r)' % (self.decider, self.yes, self.no)
class Parameter(utils.OrderedBase):
"""A complex parameter, to be used in a Factory.Params section.
Must implement:
- A "compute" function, performing the actual declaration override
- Optionally, a get_revdeps() function (to compute other parameters it may alter)
"""
def as_declarations(self, field_name, declarations):
"""Compute the overrides for this parameter.
Args:
- field_name (str): the field this parameter is installed at
- declarations (dict): the global factory declarations
Returns:
dict: the declarations to override
"""
raise NotImplementedError()
def get_revdeps(self, parameters):
"""Retrieve the list of other parameters modified by this one."""
return []
class SimpleParameter(Parameter):
def __init__(self, value):
self.value = value
def as_declarations(self, field_name, declarations):
return {
field_name: self.value,
}
@classmethod
def wrap(cls, value):
if not isinstance(value, Parameter):
return cls(value)
return value
[docs]class Trait(Parameter):
"""The simplest complex parameter, it enables a bunch of new declarations based on a boolean flag."""
def __init__(self, **overrides):
super(Trait, self).__init__()
self.overrides = overrides
def as_declarations(self, field_name, declarations):
overrides = {}
for maybe_field, new_value in self.overrides.items():
overrides[maybe_field] = Maybe(
decider=SelfAttribute(
'%s.%s' % (
'.' * maybe_field.count(enums.SPLITTER),
field_name,
),
default=False,
),
yes_declaration=new_value,
no_declaration=declarations.get(maybe_field, SKIP),
)
return overrides
def get_revdeps(self, parameters):
"""This might alter fields it's injecting."""
return [param for param in parameters if param in self.overrides]
def __repr__(self):
return '%s(%s)' % (
self.__class__.__name__,
', '.join('%s=%r' % t for t in self.overrides.items())
)
# Post-generation
# ===============
class PostGenerationDeclaration(utils.OrderedBase):
"""Declarations to be called once the model object has been generated."""
def call(self, instance, step, context): # pragma: no cover
"""Call this hook; no return value is expected.
Args:
obj (object): the newly generated object
create (bool): whether the object was 'built' or 'created'
context: a builder.PostGenerationContext containing values
extracted from the containing factory's declaration
"""
raise NotImplementedError()
[docs]class PostGeneration(PostGenerationDeclaration):
"""Calls a given function once the object has been generated."""
def __init__(self, function):
super(PostGeneration, self).__init__()
self.function = function
def call(self, instance, step, context):
logger.debug(
"PostGeneration: Calling %s.%s(%s)",
self.function.__module__,
self.function.__name__,
utils.log_pprint(
(instance, step),
context._asdict(),
),
)
create = step.builder.strategy == enums.CREATE_STRATEGY
return self.function(
instance, create, context.value, **context.extra)
class NotProvided:
pass
[docs]class PostGenerationMethodCall(PostGenerationDeclaration):
"""Calls a method of the generated object.
Attributes:
method_name (str): the method to call
method_args (list): arguments to pass to the method
method_kwargs (dict): keyword arguments to pass to the method
Example:
class UserFactory(factory.Factory):
...
password = factory.PostGenerationMethodCall('set_pass', password='')
"""
def __init__(self, method_name, *args, **kwargs):
super(PostGenerationMethodCall, self).__init__()
if len(args) > 1:
raise errors.InvalidDeclarationError(
"A PostGenerationMethodCall can only handle 1 positional argument; "
"please provide other parameters through keyword arguments."
)
self.method_name = method_name
self.method_arg = args[0] if args else NotProvided
self.method_kwargs = kwargs
def call(self, instance, step, context):
if not context.value_provided:
if self.method_arg is NotProvided:
args = tuple()
else:
args = tuple([self.method_arg])
else:
args = tuple([context.value])
kwargs = dict(self.method_kwargs)
kwargs.update(context.extra)
method = getattr(instance, self.method_name)
logger.debug(
"PostGenerationMethodCall: Calling %s.%s(%s)",
utils.log_repr(instance),
self.method_name,
utils.log_pprint(args, kwargs),
)
return method(*args, **kwargs)