django-eav2/eav/decorators.py

133 lines
3.7 KiB
Python

from functools import wraps
from django.db import models
from .models import Attribute, Value
def register_eav(**kwargs):
"""
Registers the given model(s) classes and wrapped Model class with
django-eav:
@register_eav
class Author(models.Model):
pass
"""
from . import register
from django.db.models import Model
def _model_eav_wrapper(model_class):
if not issubclass(model_class, Model):
raise ValueError('Wrapped class must subclass Model.')
register(model_class, **kwargs)
return model_class
return _model_eav_wrapper
def eav_filter(func):
'''
Decorator used to wrap filter and exclude methods. Passes args through
expand_q_filters and kwargs through expand_eav_filter. Returns the
called function (filter or exclude).
'''
@wraps(func)
def wrapper(self, *args, **kwargs):
nargs = []
nkwargs = {}
for arg in args:
if isinstance(arg, models.Q):
# Modify Q objects (warning: recursion ahead).
# import pdb; pdb.set_trace()
arg = expand_q_filters(arg, self.model)
nargs.append(arg)
o = self.model.objects.all().first()
fn = self.model.objects.filter
# print(args, kwargs)
for key, value in kwargs.items():
# Modify kwargs (warning: recursion ahead).
nkey, nval = expand_eav_filter(self.model, key, value)
if nkey in nkwargs:
# Apply AND to both querysets.
nkwargs[nkey] = (nkwargs[nkey] & nval).distinct()
else:
nkwargs.update({nkey: nval})
return func(self, *nargs, **nkwargs)
return wrapper
def expand_q_filters(q, root_cls):
'''
Takes a Q object and a model class.
Recursivley passes each filter / value in the Q object tree leaf nodes
through expand_eav_filter
'''
new_children = []
for qi in q.children:
if type(qi) is tuple:
# this child is a leaf node: in Q this is a 2-tuple of:
# (filter parameter, value)
key, value = expand_eav_filter(root_cls, *qi)
new_children.append(models.Q(**{key: value}))
else:
# this child is another Q node: recursify!
new_children.append(expand_q_filters(qi, root_cls))
_q = models.Q()
_q.children = new_children
_q.connector = q.connector
_q.negated = q.negated
return _q
def expand_eav_filter(model_cls, key, value):
'''
Accepts a model class and a key, value.
Recurisively replaces any eav filter with a subquery.
For example::
key = 'eav__height'
value = 5
Would return::
key = 'eav_values__in'
value = Values.objects.filter(value_int=5, attribute__slug='height')
'''
fields = key.split('__')
config_cls = getattr(model_cls, '_eav_config_cls', None)
if len(fields) > 1 and config_cls and \
fields[0] == config_cls.eav_attr:
slug = fields[1]
gr_name = config_cls.generic_relation_attr
datatype = Attribute.objects.get(slug=slug).datatype
lookup = '__%s' % fields[2] if len(fields) > 2 else ''
kwargs = {'value_%s%s' % (datatype, lookup): value,
'attribute__slug': slug}
value = Value.objects.filter(**kwargs)
return '%s__in' % gr_name, value
try:
field = model_cls._meta.get_field(fields[0])
except models.FieldDoesNotExist:
return key, value
if not field.auto_created or field.concrete:
return key, value
else:
sub_key = '__'.join(fields[1:])
key, value = expand_eav_filter(field.model, sub_key, value)
return '%s__%s' % (fields[0], key), value