On 20 November 2010 02:51, Micah Carrick <mi...@greentackle.com> wrote:
> I'm having trouble coming up with a pretty solution to a seemingly simple
> task. I'm relatively new to Django.
>
> I want to allow the end user to control various lists of links on the site
> used for navigation. The admin should allow the creation of "link groups"
> which have a collection of "links". These links would reference a
> pre-determined list of models. Let's say, for example, that there is a "link
> group" created for the footer links of a website. In the admin section, a
> user could add a link to a specific blog (from the Blog model), another link
> to the about us page (flatpages), etc.
>
> In other words, I'm trying to associate individual records from a number of
> tables together as a group of objects having a URL. I'm trying to find a
> nice, abstract solution. Obviously I don't want actual URLs in the database.
> This is something I would use frequently so I want to see if I can find or
> write an app to do this--if I can come up with an elegant solution.
>
> This would be nice, but, I can't imagine how it could be possible:
>
>
> class LinkGroup(models.Model):
> site = models.ForeignKey(Site)
> name = models.CharField()
>
> class Links(models.Model):
> link_group = ForeignKey(LinkGroup)
> model_type = ???
> model_id = ForeignKey(<to the PK of the above the model_type>) # no can
> do!
> sort_order = PositiveIntegerField(default=100)
>
>
> This is an idea, however, I don't like having to reference the import in the
> DB. It's just begging for problems.
>
>
> class LinkModel(models.Model):
> name = models.CharField() # such as "Flat Page"
> model = models.CharField() # such as "myapp.models.FlatPage"
>
> class LinkGroup(models.Model):
> site = models.ForeignKey(Site)
> name = models.CharField() # such as "Navigation Links"
>
> class Link(models.Model):
> text = CharField() # such as "About Us"
> link_group = ForeignKey(LinkGroup)
> model = ForeignKey(LinkModel)
> model_id = PositiveIntegerField() # such as the PK for the
> myapp.models.FlatPage model
> sort_order = PositiveIntegerField(default=100)
>
>
> Any suggestions?
You should checkout generic foreign keys[1]. It's a standard way of
building models that need to reference rows in more then one table. So
your models would be something like this:
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes import generic
class LinkGroup(models.Model):
site = models.ForeignKey(Site)
name = models.CharField() # such as "Navigation Links"
class Link(models.Model):
link_group = ForeignKey(LinkGroup)
content_type = models.ForeignKey(ContentType)
object_id = models.PositiveIntegerField()
linked_object = generic.GenericForeignKey('content_type', 'object_id')
[1]:
http://docs.djangoproject.com/en/dev/ref/contrib/contenttypes/#generic-relations
--
Łukasz Rekucki
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