On Fri, Jan 30, 2009 at 7:30 AM, Jason Geiger <jgei...@nother.net> wrote: > > Hello all. Say I have some models like these: > > class Image(models.Model): > file = models.ImageField(upload_to=get_image_path) > > class Line(models.Model): > image = models.ForeignKey(Image) > color = models.CharField(max_length=20) > width = models.IntegerField() > > class Point(models.Model): > line = models.ForeignKey(Line) > ordering = models.IntegerField() > x = models.IntegerField() > y = models.IntegerField() > > And I want to load an image and all its lines into the interface, add > and remove lines, and then send it back to the controller. > > What's the django-ish way to serialize data like this? > > The default serializers doesn't seem to do relationships. I saw > discussion[1] of one that does foreign keys but it seems to be going > to in the opposite direction I want (and it doesn't deserialize yet?).
It depends on exactly what you mean by serialize. The Django serializers will produce JSON/XML/YAML output on demand, and on each object instance they will include Foreign key and ManyToMany relationships. The format that the Django serializers output may not be appropriate for every application. The default format is very well suited to use in test fixtures - since that is one of the major use cases for serialization in the Django core framework. The default serialization format may not be well suited to other applications. > Stepping back, is this sort of thing that you'd be expected to do with > a custom serializer? Or is it better to just serialize each set of > data separately and save them separately. I started by using > simplejson directly but then was wondering about the built-in > serialization code in Django. It very much depends on your specific requirements. "Serialization" is a very usage-dependent behaviour. In your case, if you are in control of both sender and receiver, you may be able to use the Django serializers. Serialize at one end, deserialize at the other end, manipulate, then repeat in reverse. What Django won't do is gather the objects you need to serialize. Django can serialize a list of objects, but it doesn't currently contain any code to follow relationship chains and gather related objects. For example, if you want to serialize one of your image objects, you will need to write the code to find all the related lines (and points?), collect them into a list, and pass that complete list to Django's serializers. Implementing this 'relationship following' behaviour is a long standing feature request (see ticket #4656) [1]. However, nobody has presented a complete patch yet, and the core developers have had other development priorities, so this particular issue has been languishing for attention. In your case, the simplest option will be to build some instance collection code that inspects your known model structure an collects the appropriate object instances. However, if you feel like trying your hand at the general case, patches are welcome :-) [1] http://code.djangoproject.com/ticket/4656 Yours, Russ Magee %-) --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
