Changes between Initial Version and Version 1 of CookBookCategoryDataModelPostMagic

Timestamp:

May 18, 2006, 11:34:16 PM (20 years ago)

Author:

anonymous

Comment:

--

CookBookCategoryDataModelPostMagic

@@ +1 @@
+= CookBook - Data Model =
+
+== A "category" Data Model ==
+
+== Description ==
+I like to have parent/child categories for my documents and weblog entries. I also am a fan of simplicity. This recipe lets you create new categories, and children of categories while providing an intuitively obvious presentation to the user. A parent category of 'Development' with a child category of 'Python' will be displayed as 'Development :: Python'. Using that example, other data models/content types that utilize this code will have drop-downs in the admin interface with entries of 'Development' and 'Development :: Python'
+
+== Code ==
+{{{
+#!python
+class Category(models.Model):
+        name = models.CharField(core=True, maxlength=200)
+        slug = models.SlugField(prepopulate_from=('name',))
+        parent = models.ForeignKey('self', blank=True, null=True, related_name='child')
+        description = models.TextField(blank=True,help_text="Optional")
+        
+        class Admin:
+                list_display = ('name', '_parents_repr')
+        
+        def __str__(self):
+                p_list = self._recurse_for_parents(self)
+                p_list.append(self.name)
+                return self.get_separator().join(p_list)
+        
+        def get_absolute_url(self):
+                if self.parent_id:
+                        return "/tag/%s/%s/" % (self.parent.slug, self.slug)
+                else:
+                        return "/tag/%s/" % (self.slug)
+        
+        def _recurse_for_parents(self, cat_obj):
+                p_list = []
+                if cat_obj.parent_id:
+                        p = cat_obj.parent
+                        p_list.append(p.name)
+                        more = self._recurse_for_parents(p)
+                        p_list.extend(more)
+                if cat_obj == self and p_list:
+                        p_list.reverse()
+                return p_list
+                
+        def get_separator(self):
+                return ' :: '
+        
+        def _parents_repr(self):
+                p_list = self._recurse_for_parents(self)
+                return self.get_separator().join(p_list)
+        _parents_repr.short_description = "Tag parents"
+        
+        def save(self):
+                p_list = self._recurse_for_parents(self)
+                if self.name in p_list:
+                        raise validators.ValidationError("You must not save a category in itself!")
+                super(Tag, self).save()
+}}}
+
+== See Also ==
+
+http://www.djangoproject.com/documentation/model_api/
+
+http://www.djangoproject.com/documentation/models/m2o_recursive/
+