Trouble understanding why django tastypie POST fails with a 500 Internal Error

Question

Just got introduced to django tastypie and having trouble sending data.I have a django model,

class OrderItem(SmartModel):
    shopping_id = models.CharField(max_length=255,db_index=True)
    quantity = models.IntegerField()
    item = models.ForeignKey(Item)
    option = models.ForeignKey(OptionalItem,null=True,blank=True)
    toppings_and_extras = models.ManyToManyField(ToppingsAndExtra,null=True, blank=True)

and the tastypie resource,

class OrderItemResource(ModelResource):
    item = fields.ToOneField(ItemResource,'item',null=False,blank=False,full=True)
    option = fields.ToOneField(OptionResource,'option',null=True,blank=True,full=True)
    toppings_and_extras = fields.ToManyField(ToppingResource,'toppings_and_extras',null=True,blank=True,full=True)
    class Meta:
        queryset = OrderItem.objects.all()
        resource_name = 'order'
        authorization = Authorization()
        always_return_data =True

I perform a test POST as illustrated in the tastypie docs,

curl --dump-header - -H "Content-Type: application/json" -X POST --data '{"shopping_id":"(TBH5@Y4NQDD$PJWUCQ4WEG3%CL0RSDPUD%EDQ!EG$81^WXSV6^URBC0OO45OC(IV)QW7WC(W0GD9)N&5HXLA1)8M1IHGWQ4A&P1","quantity":"5","item":"/api/v1/menu_item/1/","option":"/api/v1/options/1/","created_by":"/api/v1/user/1/","modified_by_id":"/api/v1/user/1/","toppings_and_extra":"[]"}' http://localhost:8000/api/v1/order/

The request responds with an error "current transaction is aborted",looking at the logs, the error their is null value in column "created_by_id" violates not-null constraint. This is what i don't understand, because i thought by adding "created_by":"/api/v1/user/1/" takes care of the problem. What am i not doing right, my research is limited because i cannot seem to understand what is going wrong. Links to helpful information in docs is also appreciated.

Answer 1

To access any relation field you have to define it in ModelResource.

class OrderItemResource(ModelResource):
    created_by = fields.ToOneField(UserResource,'created_by')
    [...]

    class Meta:
        queryset = OrderItem.objects.all()
        resource_name = 'order'
        authorization = Authorization()
        always_return_data =True

The reason why you have to do it is that Tastypie has to know ModelResource definition of that model: resource name, query set and authorization access among others. Without it Tastypie will ignore it.

If you haven't defined UserResource yet, you should do it.

I see you are using base model for all models: "SmartModel". I think the best for you will be creation of base model resource to inherit. "SmartModelResource" and you will define needed fields there.

class SmartModelResource(ModelResource):
    created_by = fields.ToOneField(UserResource,'created_by')
    [...]


class OrderItemResource(SmartModelResource):
    [...]

    class Meta:
        queryset = OrderItem.objects.all()
        resource_name = 'order'
        authorization = Authorization()
        always_return_data =True