Hello,
My problem is very rare so I'll try ad add as much useful detail as
possible.
I am using python 3.5 and 3.6, Django 1.11.4
I am creating complex security related application and need to generate
additional models based on other applications' models. In general,
everything works fine, models are created, migrated without a problem. But
there is single problem I totally failed to solve.
Let's say there is preexisting model Alpha of some other application and I
dynamically create model Beta which references Alpha with ForeignKey. The
problem is that Beta does not get reverse relation, so I can query for
beta.alpha, but not for alpha.betas. I receive
"django.core.exceptions.FieldError: Cannot resolve keyword 'betas' into
field. Choices are: x, y, z"
Here is my code
* def _create_dynamic_model(self, model_label, fields, attributes=None,
options=None): from django.db import models class
Meta: pass setattr(Meta, 'app_label', '_talos') if
options is not None: for key, value in
options.items(): setattr(Meta, key, value) attrs =
{'__module__': '_talos', '_talos_dynamic': True, 'Meta': Meta} if
attributes: attrs.update(attributes) if
fields: attrs.update(fields) model = type(model_label,
(models.Model,), attrs) return model*
I call it like this (where self.model is referenced model class)
def _create_object_permission_model(self):
from django.db import models
return self._create_dynamic_model(
'o_{0}_{1}'.format(self.model._meta.app_config.label,
self.model.__name__),
fields={
'role': models.ForeignKey(
'talos.Role',
related_name='+',
on_delete=models.CASCADE),
'permission': models.ForeignKey(
'talos.ObjectPermission',
related_name='+',
on_delete=models.CASCADE),
'target': models.ForeignKey(
self.model,
related_name='talos_permissions', # self.model does not
receive reverse relation!
on_delete=models.CASCADE)
},
options={
'unique_together': [('role', 'permission', 'target')],
'index_together': [
('target', 'permission', 'role'),
('target', 'role', 'permission'),
('role', 'target', 'permission')]
})
I tried calling contribute_to_class and contribute_to_related_class methods
manually, tried to call this code at different moments (My application
ready method, class_prepared signal handler), with absolutely no luck.
I tried to read Django sources, and got that contribute_to_related_class is
called from contribute_to_class with delay, but it did not help me realize
what exactly I am doing wrong.
I am trying to use reverse relation from custom view and admin, so
everything should be pretty much initialized already.
Roman
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