Ticket #23624: models.py

import sys

from types import ModuleType

from django.db import models

# db schema and traceback at the bottom

"""
>>> from modeltest.models import get_module
>>> 
>>> m = get_module()
>>> m.A(id=1, name='a').save()
>>> m.B(id=1, name='b').save()
>>> m.AB(a=m.A.objects.get(id=1), b=m.B.objects.all()[0], extra='ab').save()
>>> m.AB.objects.select_related('a', 'b') # works in both 1.6 and 1.7
>>> m.A.objects.get(id=1).b_s.all() # works in 1.6, raises FieldError in 1.7
>>>
"""


class A(models.Model):
    id = models.IntegerField(primary_key=True, db_column='a_primary_id')
    name = models.CharField(max_length=12)
    b_s = models.ManyToManyField('B', through='AB')

    class Meta:
        abstract = True


class B(models.Model):
    id = models.IntegerField(primary_key=True, db_column='b_primary_id')
    name = models.CharField(max_length=12)
    a_s = models.ManyToManyField('A', through='AB')

    class Meta:
        abstract = True

class AB(models.Model):
    a = models.ForeignKey('A', db_column='rel_to_a')
    b = models.ForeignKey('B', db_column='rel_to_b')
    extra = models.CharField(max_length=12, blank=True, null=True)

    class Meta:
        unique_together = (('a', 'b'),)
        abstract = True

        
def get_module():
    name = 'modeltest_dynamic.models'
    
    if name in sys.modules:
        return sys.modules[name]
    
    mod = ModuleType(name)

    mod.A = type('A', (A,), {
        '__module__':mod.__name__,
        'Meta':type('Meta', (A.Meta, object), {
            '__module__':mod.__name__,
            'app_label':'modeltest_dynamic',
            'managed':False,
            'db_table':A._meta.db_table
        })
    })

    mod.B = type('B', (B,), {
        '__module__':mod.__name__,
        'Meta':type('Meta', (B.Meta, object), {
            '__module__':mod.__name__,
            'app_label':'modeltest_dynamic',
            'managed':False,
            'db_table':B._meta.db_table
        })
    })

    mod.AB = type('AB', (AB,), {
        '__module__':mod.__name__,
        'Meta':type('Meta', (AB.Meta, object), {
            '__module__':mod.__name__,
            'app_label':'modeltest_dynamic',
            'managed':False,
            'db_table':AB._meta.db_table
        })
    })
    
    sys.modules[name] = mod
    return mod


"""
CREATE TABLE "modeltest_a" (
    "a_primary_id" integer NOT NULL PRIMARY KEY,
    "name" varchar(12) NOT NULL
);
CREATE TABLE "modeltest_b" (
    "b_primary_id" integer NOT NULL PRIMARY KEY,
    "name" varchar(12) NOT NULL
);
CREATE TABLE "modeltest_ab" (
"id" integer NOT NULL PRIMARY KEY AUTOINCREMENT,
"rel_to_a" integer NOT NULL REFERENCES "modeltest_a" ("a_primary_id"),
"rel_to_b" integer NOT NULL REFERENCES "modeltest_b" ("b_primary_id"),
"extra" varchar(12),
UNIQUE ("rel_to_a", "rel_to_b")
);
CREATE INDEX "modeltest_ab_4d6cc2fb" ON "modeltest_ab" ("rel_to_a");
CREATE INDEX "modeltest_ab_2c14050b" ON "modeltest_ab" ("rel_to_b");
"""

"""
Django 1.7
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-packages/django/db/models/manager.py", line 191, in all
    return self.get_queryset()
  File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-packages/django/db/models/fields/related.py", line 887, in get_queryset
    return qs._next_is_sticky().filter(**self.core_filters)
  File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-packages/django/db/models/query.py", line 691, in filter
    return self._filter_or_exclude(False, *args, **kwargs)
  File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-packages/django/db/models/query.py", line 709, in _filter_or_exclude
    clone.query.add_q(Q(*args, **kwargs))
  File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1287, in add_q
    clause, require_inner = self._add_q(where_part, self.used_aliases)
  File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1314, in _add_q
    current_negated=current_negated, connector=connector)
  File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1138, in build_filter
    lookups, parts, reffed_aggregate = self.solve_lookup_type(arg)
  File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1076, in solve_lookup_type
    _, field, _, lookup_parts = self.names_to_path(lookup_splitted, self.get_meta())
  File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1383, in names_to_path
    self.raise_field_error(opts, name)
  File "/home/ludo/Desktop/dev/venv/spritz/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1389, in raise_field_error
    "Choices are: %s" % (name, ", ".join(available)))
FieldError: Cannot resolve keyword u'a' into field. Choices are: a_s, id, name
"""