Re: Serialize model properties enhancement
On 4/28/07, David Elias <[EMAIL PROTECTED]> wrote: > > > > On Apr 28, 2:48 am, "Russell Keith-Magee" <[EMAIL PROTECTED]> > wrote: > > The open question in my mind is where the serialized data goes - do we > > put it into the fields block, or do we start a new 'extra' block? i.e, > > which of the following JSON outputs would you expect? > > I prefer the latter too, with the extra block. > > > And what happens on deserialization? Is the attribute restored, or > > ignored? I'm inclined to prefer the latter serialization format, and > > ignore on restoration, but I'd be interested in hearing other > > opinions. > > Regarding deserialization, i guess if a queryset will set these extra > columns to a model why not restore them? Two reasons - one practical, one philosophical. Practical: If you go down Oyvind's path, and serialize a property that has a getter, but not a setter, you could get some interesting fireworks on reserialization. Philosophical: The purpose of deserialization is to get data back into the database. Since the 'extra' attributes won't/can't ever be saved to the database, my gut reaction is that we should avoid the appearance that these extra attributes are 'normal' in any way - refusing to deserialize them is just one way of achieving this separation. Yours, Russ Magee %-) --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-developers@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-developers?hl=en -~--~~~~--~~--~--~---
Re: Serialize model properties enhancement
On Apr 28, 2:48 am, "Russell Keith-Magee" <[EMAIL PROTECTED]> wrote: > The open question in my mind is where the serialized data goes - do we > put it into the fields block, or do we start a new 'extra' block? i.e, > which of the following JSON outputs would you expect? I prefer the latter too, with the extra block. > And what happens on deserialization? Is the attribute restored, or > ignored? I'm inclined to prefer the latter serialization format, and > ignore on restoration, but I'd be interested in hearing other > opinions. Regarding deserialization, i guess if a queryset will set these extra columns to a model why not restore them? David Elias --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-developers@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-developers?hl=en -~--~~~~--~~--~--~---
Re: Serialize model properties enhancement
On 4/28/07, David Elias <[EMAIL PROTECTED]> wrote:
>
> Russell Keith-Magee escreveu:
> > On 3/17/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> > I'm afraid I don't see the benefit of what you are proposing. The
> > serialization framework exists for the easy serialization of Django
> > DB-backed objects - not for the arbitrary serialization of _any_
> > object, and derived properties like the ones you are highlighting as
> > examples don't add anything to the serialized representation of a
> > DB-backed object.
>
> Sorry for bringing this again.
>
> And what about queryset's extra_select dictionary? imo makes sense,
> since we pass a queryset to the serializer.
>
> What's your opinion?
Ok; this is a different use case. You're talking about attributes on
the model that have been derived from the database, and are augmenting
the normal results from the query set. This is a use case that has
some value.
My initial reaction on how to implement this would be to mirror the
QuerySet API; add an 'extra' argument, which allows you to specify
attributes that you want to have serialized.
The open question in my mind is where the serialized data goes - do we
put it into the fields block, or do we start a new 'extra' block? i.e,
which of the following JSON outputs would you expect?
[
{
"pk": "1",
"model": "auth.user",
"fields": {
"username": "jsmith",
"first_name": "John",
"last_name": "Smith",
"my_extra_select": "mydata"
}
}
]
or
[
{
"pk": "1",
"model": "auth.user",
"fields": {
"username": "jsmith",
"first_name": "John",
"last_name": "Smith"
},
"extra": {
"my_extra_select": "mydata"
}
}
]
And what happens on deserialization? Is the attribute restored, or
ignored? I'm inclined to prefer the latter serialization format, and
ignore on restoration, but I'd be interested in hearing other
opinions.
Yours,
Russ Magee %-)
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Re: Serialize model properties enhancement
On 3/17/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > I am in no way saying this should be default behaviour of the > serializers, but as a option, making a own serializer for theese cases > is possible, but this makes it a lot of more work for something that > could be so DRY. Again, what you are proposing (and your example) is very explicitly _not_ DRY. In this example, the preview property repeats data that is held canonically in the image attribute. DRY would dictate that you use the image attribute, rather than serializing a completely derived attribute. I'm afraid I don't see the benefit of what you are proposing. The serialization framework exists for the easy serialization of Django DB-backed objects - not for the arbitrary serialization of _any_ object, and derived properties like the ones you are highlighting as examples don't add anything to the serialized representation of a DB-backed object. For the use-case you describe - XMLRPC and similar calls - you need to adhere to a specific API. It would expect it to be very unusual for the requirements of an RPC API to match the serialization strategy of a Django object. For these problems, you need to serialize a very specific set of object-related information (not the object itself) in a very specific format; the better approach in this cases would be to construct a dictionary that explicitly contains the data you want, and use the SimpleJSON/PyYAML/XML libraries natively to serialize the dictionary into the desired format. Yours, Russ Magee %-) --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-developers@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-developers?hl=en -~--~~~~--~~--~--~---
Re: Serialize model properties enhancement
It is really great for including get_FOO_url or getting data from related models without making custom serializers when serializing to json or xml for xmlhttp requests. class Gallery(models.Model): name = models.CharField() def _preview(self): try: image = self.image_set.all()[0].get_preview_url() except: image = None return image preview = property(_preview) class Image(models.Model): gallery = models.ForeignKey(Gallery) preview = models.ImageField(upload_to='foo') I am in no way saying this should be default behaviour of the serializers, but as a option, making a own serializer for theese cases is possible, but this makes it a lot of more work for something that could be so DRY. On 16 Mar, 23:41, "Russell Keith-Magee" <[EMAIL PROTECTED]> wrote: > On 3/17/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > > > > I think the serializers should have a option for serializing model > > properties > > > This is set to design decision needed, does this seem like something > > django needs? > > >http://code.djangoproject.com/ticket/3661 > > In the example you give on this ticket, the property myattr is > directly derived from the database value mydescription - I can't see > any value in serializing both values. > > Even if the property wasn't a simple derivation of the database value > - if data isn't part of the database definition, it will be extremely > transient, and as soon as the instance is lost, so is the property > data. Again, I can't see any value in making that data a permanent > part of a serialized representation. > > Am I missing something here? > > Yours, > Russ Magee %-) --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-developers@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-developers?hl=en -~--~~~~--~~--~--~---
Re: Serialize model properties enhancement
On 3/17/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > I think the serializers should have a option for serializing model > properties > > This is set to design decision needed, does this seem like something > django needs? > > http://code.djangoproject.com/ticket/3661 In the example you give on this ticket, the property myattr is directly derived from the database value mydescription - I can't see any value in serializing both values. Even if the property wasn't a simple derivation of the database value - if data isn't part of the database definition, it will be extremely transient, and as soon as the instance is lost, so is the property data. Again, I can't see any value in making that data a permanent part of a serialized representation. Am I missing something here? Yours, Russ Magee %-) --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-developers@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-developers?hl=en -~--~~~~--~~--~--~---
Serialize model properties enhancement
I think the serializers should have a option for serializing model properties This is set to design decision needed, does this seem like something django needs? http://code.djangoproject.com/ticket/3661 --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-developers@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-developers?hl=en -~--~~~~--~~--~--~---
