A Model to store links to other models
Micah Carrick
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?
Steve Holden
pages in sections at http://holdenweb.com/ - here are the relevant models:
class Section(models.Model):
secid = models.IntegerField(primary_key=True) # This field type is
corrected
sectitle = models.CharField(max_length=50)
secpath = models.CharField(max_length=50)
secbgcolor = models.CharField(max_length=50)
secstcolor = models.CharField(max_length=50)
secpos = models.CharField(max_length=1)
secsequence = models.IntegerField() # This field type is corrected
sechandler = models.CharField(max_length=50)
sechomeslot = models.IntegerField() # This field type is corrected
sechometitle = models.CharField(max_length=50)
secnews = models.CharField(max_length=20, null=True)
class Meta:
db_table = 'section'
unique_together = (('secpath', ), ('sectitle', ))
class Admin:
list_display = ('sectitle', )
def __str__(self):
return self.sectitle
class Page(models.Model):
pagpath = models.CharField(primary_key=True, max_length=50)
pagdoctitle = models.CharField(max_length=250)
pagtitle = models.CharField(max_length=200, blank=True, null=True)
pagsecid = models.ForeignKey(Section, blank=True, null=True,
db_column='pagsecid') # This field
type is corrected
pagsequence = models.IntegerField() # This field type is corrected
pagtplname = models.CharField(max_length=50)
paggenerated = models.SmallIntegerField()
paglinkpath = models.CharField(max_length=50, blank=True, null=True)
pagcontent = models.TextField()
pagnavbarstuff = models.TextField(null=True, blank=True)
pagctype = models.CharField(max_length=1, default="R") # This field
type is corrected
pagid = models.IntegerField() # Note this should eventually become
the PK
pagnews = models.CharField(max_length=20, blank=True, null=True)
class Meta:
db_table = 'page'
def __str__(self):
return self.pagpath
What is it that the first model didn't do for you?
regards
Steve
--
DjangoCon US 2010 September 7-9 http://djangocon.us/
Mark (Nosrednakram)
I'm not sure I understand what you're attempting to do but if so I'd
look at using a foreign key to ContentType, and storing the pk for
associating objects rather than a CharField. The key is using
ContentType.model_class() to re-create the class. This allows you to
store any object using two fields and re-generate it easly in two
calls.
Hope This Helps,
Mark
Łukasz Rekucki
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
Micah Carrick
Thanks everybody!
--
You received this message because you are subscribed to the Google Groups "Django users" group.
To post to this group, send email to django...@googlegroups.com.
To unsubscribe from this group, send email to django-users...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
Micah Carrick
I could use some advice on the next steps for the administration. I am passing the link groups to the template via context so that the template can iterate over each group creating a unordered list of links for each group. Some links are blog posts, some are flat pages, etc. Works great. However, there are two parts of the admin I could use some guidance on. Links to docs, blogs, or example code would be great.
First, in the drop down list for the ContentType, I need to exclude any object that do not define get_absolute_url. In other words, only models that can be linked to should be allowed.
Second, and this may be more difficult, the object_id field requires the admin user to know the PK of the object their linking to, which they most certainly will not. However, I don't know how that could be determined without first knowing which content_type they select-- AJAX is the only thing I can think of. Thoughts?
class LinkGroup(models.Model):
site = models.ForeignKey(Site)
template_var = models.CharField(max_length=25, unique=True, db_index=True)
heading = models.CharField(max_length=100, blank=True, null=True)
def __unicode__(self):
return self.template_key
class Meta():
db_table = 'link_group'
class LinkObject(models.Model):
text = models.CharField(max_length=50) # text for the link
link_group = models.ForeignKey(LinkGroup)
content_type = models.ForeignKey(ContentType)
object_id = models.PositiveIntegerField()
sort_order = models.PositiveIntegerField(default=100)
def __unicode__(self):
return self.text
class Meta():
db_table = 'link_object'
class LinkGroupInline(admin.TabularInline):
model = LinkObject
class LinkGroupAdmin(admin.ModelAdmin):
inlines = [
LinkGroupInline
]
admin.site.register(LinkGroup, LinkGroupAdmin)
Micah Carrick, Founder
Green Tackle - Environmentally Friendly Fishing Tackle
www.GreenTackle.com
Email: mi...@greentackle.com
Phone: 971.270.2206
Toll Free: 877.580.9165
Fax: 503.946.3106