Feature Request: Allow Serialize Foreign Keys as Ids

[Ryan Gartin]

I came across this issue calling the following and FK fields with _id are 
ignored:
serialize('json', , fields=['title', 'state_id']). 

State is a ForeignKey on my queryset. I can perform fields=['title', 
'state'] and I get serialization correctly of {'state': int}. However, if I 
specify fields=['state_id'] then the serialization completely ignores that 
field. It would be nice if we could serialize foreign keys on either 
field.name or field.attname. 

I wrote a hack to make it work myself but it breaks the non-id use case.

def start_serialization(self):
for field in [x for x in self.selected_fields if '_id' in x]:
self.selected_fields.append(field.replace('_id', ''))
super().start_serialization()

def handle_fk_field(self, obj, field):
if not self.use_natural_foreign_keys and not hasattr
(field.remote_field.model, "natural_key"):
self._current[field.attname] = getattr(obj, field.attname)
else:
return super().handle_fk_field(obj, field)

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Re: Feature Request: Allow Serialize Foreign Keys as Ids

[Ryan Gartin]

You are correct state_id is not a field on the model, state is, and using “
state” in the field lists works.

I would like to propose that if  ‘state_id’ is a valid property on the 
queryset (and in the database) that is should be serialized.

It is my preference that a serialized JSON property (to be consumed in a 
strongly typed language) is reserved for a specific type. I realize Django 
will determine that `state: int` is an Int and it needs to do a FK lookup 
and populate that property with the state model but a strongly typed 
language does not have that ability to determine between two types nor does 
it have the ability to requery. So my preference when I consume JSON 
response into my apps is to reserve state: { title: str, etc...} to an 
object representing State model and use state_id: int wherever I just need 
the Integer. 

While I understand that this is my personal preference I think it is 
reasonable to request that if QuerySet.state_id returns a valid value then 
it should also be capable of being serialized as well. 

On Thursday, August 3, 2023 at 9:46:27 PM UTC-4 Curtis Maloney wrote:

> Hi Mike,
>
> On Fri, 4 Aug 2023, at 06:03, Ryan Gartin wrote:
>
> I came across this issue calling the following and FK fields with _id are 
> ignored:
> serialize('json', , fields=['title', 'state_id']). 
>
>
> I think the problem you've run into here is "state_id" is not a Field on 
> your model; it's where the raw PK value for your ForeignKey is stored.
>
> I've just double checked the code for serialize, and I'm pretty sure the 
> default behavior for a ForeignKey field _is_ _already_ to output the PK 
> value.
>
> What happens in your code if you put "state" instead of "state_id" in the 
> field list?
>
> --
> Curtis
>

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