Russ,
Thanks for the reply. Specifically, I am wondering if there is some
feature of the Models API that allows me to retrieve the foreign key
object so that it is included in the serialized string. That is,
without writing my own serializer (which I suspect I may have to do).
Alternatively, I was hoping somebody may be able to offer a technique
for passing messages that I may have overlooked. With queries such as
those in my example, I may be retrieving m Type objects, each of which
may have n unique Class objects with foreign key pointers, leading to
a whole mess of data to be passed in the json, making it a nightmare
to deserialize it on the other end.
Throughout my application, I am using SimpleJSON for some queries, and
serializers.serialize for others. SimpleJSON is useful for python
dictionaries and serializers.serialize is good for QuerySets.
Ultimately, though, all the information I am passing is retrieved from
QuerySets; my choice of serializer is based on whether I am iterating
through the QuerySets and writing the data to python dictionaries
(simplejson) or simply passing them directly to a response object
(serializers.serialize). The reason for this is that the object vary
in complexity and sizel for simple queries, I'll just pass the whole
QuerySet to serialize() and for complex ones I'll break it down and
create a dictionary to pass through simplejson.
I suppose that my overall intent is a cry for help for a simpler, one-
size-fits-all solution that can allow me to easily serialize objects,
yet pass small messages. Perhaps a middle layer between Django and my
front end (the Google Web Toolkit) is necessary. The fact that GWT
only has basic JSON support doesn't help, as every message I pass
requires a custom handler to decode the JSON.
I'll keep tinkering... Let me know if you have any ideas.
Adam
On Dec 27, 4:45 am, "Russell Keith-Magee" <freakboy3...@gmail.com>
wrote:
> On Sat, Dec 27, 2008 at 2:11 PM, adambossy <adambo...@gmail.com> wrote:
>
> > I have a model that refers to a ForeignKey, e.g.:
>
> > class Template(models.Model):
> > type = models.ForeignKey(Type)
> > ...
>
> > class Type(models.Model)
> > name = models.CharField(max_length=32)
> > ...
>
> > I can fetch these objects fine using the model API.
>
> > t = Template.objects.get(id=1)
> > print t.type
> >>> <Type: Type object>
> > print t.type.id
> >>> 3
> > print t.type.name
> >>> TemplateType3
>
> > If I serialize these, I cannot get 'name.' I know Django lazily
> > retrieves these, but even by iterating or calling t.type.name, they
> > are unavailable during serialization. Is there any way to have Django
> > evaluate the ForeignKey object so that I can retrieve the field,
> > 'name?' I need fields to contain "name": "TemplateType3" (or whatever
> > it may be)! :)
>
> > from django.core import serializers
> > print serializers.serialize('json', Template.objects.get(id=1))
>
> >>> {
> > "pk": 1,
> > "model": "template",
> > "fields": {
> > "type": 3
> > }
> > },
>
> It isn't entirely clear what you're trying to do. Do you want to
> change the Django serializers so that they output:
>
> "type": "TemplateType3"
>
> If this is the case, then you will need to write your own serializer.
> Django serializes objects in a specific way, optimized for
> deserialization later on as fixtures. This output format won't suit
> many applications. If you need a different format, you will need to
> write a serializer that outputs in the format you require. Django
> ships with SimpleJSON, so you can build serialized output from
> primitives if need be. You could also use Django's serialization
> library to write your own serializer that outputs in a format of your
> choice. If your desired output format is similar to Django's default
> format, you may find that you can use django/core/serializers/json.py
> as a starting point for this implementation.
>
> Alternatively, are you trying to manipulate a deserialized object in
> some way? If this is the case, you will need to provide more specific
> details on what it is you are trying to achieve.
>
> Yours
> Russ Magee %-)
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