TastyPie data validation issue - django

Question

I wonder what is the proper way of using TastyPie validation.
I have following resource and model:
from tastypie.resources import ModelResource
class Station(models.Model):
name = models.CharField(max_length=20)
city = models.ForeignKey(City)
class StationResource(ModelResource):
city = fields.ForeignKey(CityResource, 'city')
class Meta:
queryset = caModels.Station.objects.all()
resource_name = 'Station'
authorization = Authorization()
validation=FormValidation(form_class=StationForm)
max_limit = None
And I also want to use a ModelForm to validate data:
class StationForm(forms.ModelForm):
class Meta:
model = caModels.Station
def clean_city(self):
return self.cleaned_data['city']
The following query works fine:
curl --dump-header - -H "Content-Type: application/json" -X POST --data '{"city": "/resources/City/89/", "name": "station_1", <and other fields here>}' "http://localhost:8000/resources/Station/?format=json"
HTTP/1.0 201 CREATED
Date: Thu, 06 Feb 2014 13:10:14 GMT
Server: WSGIServer/0.1 Python/2.7.4
Vary: Accept, Cookie
Content-Type: text/html; charset=utf-8
Location: http://localhost:8000/resources/Station/3/
But when I remove city from request (but this field is required) instead of message 'This field is required' I get the following traceback:
Traceback (most recent call last):
File "/home/ak/venv/main_env/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 115, in get_response
response = callback(request, *callback_args, **callback_kwargs)
File "/home/ak/venv/main_env/local/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 77, in wrapped_view
return view_func(*args, **kwargs)
File "/home/ak/venv/main_env/local/lib/python2.7/site-packages/tastypie/resources.py", line 217, in wrapper
response = callback(request, *args, **kwargs)
File "/home/ak/venv/main_env/local/lib/python2.7/site-packages/tastypie/resources.py", line 459, in dispatch_list
return self.dispatch('list', request, **kwargs)
File "/home/ak/venv/main_env/local/lib/python2.7/site-packages/tastypie/resources.py", line 491, in dispatch
response = method(request, **kwargs)
File "/home/ak/venv/main_env/local/lib/python2.7/site-packages/tastypie/resources.py", line 1357, in post_list
updated_bundle = self.obj_create(bundle, **self.remove_api_resource_names(kwargs))
File "/home/ak/venv/main_env/local/lib/python2.7/site-packages/tastypie/resources.py", line 2149, in obj_create
bundle = self.full_hydrate(bundle)
File "/home/ak/venv/main_env/local/lib/python2.7/site-packages/tastypie/resources.py", line 909, in full_hydrate
value = field_object.hydrate(bundle)
File "/home/ak/venv/main_env/local/lib/python2.7/site-packages/tastypie/fields.py", line 732, in hydrate
value = super(ToOneField, self).hydrate(bundle)
File "/home/ak/venv/main_env/local/lib/python2.7/site-packages/tastypie/fields.py", line 165, in hydrate
elif self.attribute and getattr(bundle.obj, self.attribute, None):
File "/home/ak/venv/main_env/local/lib/python2.7/site-packages/django/db/models/fields/related.py", line 389, in __get__
raise self.field.rel.to.DoesNotExist
DoesNotExist
This error happens even before I can validate the data in the form (validation is the first process of save procedure looks like).
.../tastypie/resources.py:
def obj_create(self, bundle, **kwargs):
"""
A ORM-specific implementation of ``obj_create``.
"""
bundle.obj = self._meta.object_class()
for key, value in kwargs.items():
setattr(bundle.obj, key, value)
self.authorized_create_detail(self.get_object_list(bundle.request), bundle)
bundle = self.full_hydrate(bundle)
return self.save(bundle)
def save(self, bundle, skip_errors=False):
self.is_valid(bundle)
...
Can somebody point me where I am wrong, or may be I missed something and this way of validation is completely wrong from TastyPie point of view?

Answer 1

I think your question is very interesting.
I decided to dig in a little in subject..
Here is what I've found.
The docs:
blank
As we see this description is pretty similar to what we already know from Django.
The Code base:
hydrate
If you don't say explicitly Tastypie will does "expect" this field to be there.
Short conclusion: I think about resource like something beyond the models and the Meta may be much different regards to needs, that can give you more flexibility for instance.
Potential solutions:
Say to Tastypie pass it if its blank. Anyway model validation will not pass it.
class StationResource(ModelResource):
city = fields.ForeignKey(CityResource, 'city', blank=True)
Or Add default to hydrate.
class StationResource(ModelResource):
city = fields.ForeignKey(CityResource, 'city')
def hydrate(self, bundle):
if not hasattr(bundle, 'city'):
bundle.data['city'] = None
return bundle
Conclusion: This is in fact quite misleading but on other hand Tastypie is still under development, maybe docs will cover it better or this will change or there is plan to changed it.
If you are more interested there is many issues debated on github: like this one similar to your question: issue