Question

Originally started here: Django IN query as a string result – invalid literal for int() with base 10

I have a number of apps within my site, currently working with a simple “Blog” app. I have developed a ‘Favorite’ app, easily enough, that leverages the ContentType framework in Django to allow me to have a ‘favorite’ of any type… trying to go the other way, however, I don’t know what I’m doing, and can’t find any examples for.

I’ll start off with the favorite model:

favorite/models.py

from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes import generic
from django.contrib.auth.models import User

class Favorite(models.Model):
        content_type    = models.ForeignKey(ContentType)
        object_id       = models.PositiveIntegerField()
        user            = models.ForeignKey(User)
        content_object  = generic.GenericForeignKey()

        class Admin:
                list_display = ('key', 'id', 'user')

        class Meta:
                unique_together = ("content_type", "object_id", "user")

Now, that allows me to loop through the favorites (on a user’s “favorites” page, for example) and get the associated blog objects via {{ favorite.content_object.title }}.

What I want now, and can’t figure out, is what I need to do to the blog model to allow me to have some tether to the favorite (so when it is displayed in a list it can be highlighted, for example).

Here is the blog model:

blog/models.py

from django.db import models
from django.db.models import permalink
from django.template.defaultfilters import slugify
from category.models import Category
from section.models import Section
from favorite.models import Favorite
from django.contrib.auth.models import User
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes import generic

class Blog(models.Model):
        title           = models.CharField(max_length=200, unique=True)
        slug            = models.SlugField(max_length=140, editable=False)
        author          = models.ForeignKey(User)
        homepage        = models.URLField()
        feed            = models.URLField()
        description     = models.TextField()
        page_views      = models.IntegerField(null=True, blank=True, default=0 )
        created_on      = models.DateTimeField(auto_now_add = True)
        updated_on      = models.DateTimeField(auto_now = True)

        def __unicode__(self):
                return self.title

        @models.permalink
        def get_absolute_url(self):
                return ('blog.views.show', [str(self.slug)])

        def save(self, *args, **kwargs):
                if not self.slug:
                        slug = slugify(self.title)
                        duplicate_count = Blog.objects.filter(slug__startswith = slug).count()
                        if duplicate_count:
                                slug = slug + str(duplicate_count)
                        self.slug = slug
                super(Blog, self).save(*args, **kwargs)

class Entry(models.Model):
        blog            = models.ForeignKey('Blog')
        title           = models.CharField(max_length=200)
        slug            = models.SlugField(max_length=140, editable=False)
        description     = models.TextField()
        url             = models.URLField(unique=True)
        image           = models.URLField(blank=True, null=True)
        created_on      = models.DateTimeField(auto_now_add = True)

        def __unicode__(self):
                return self.title

        def save(self, *args, **kwargs):
                if not self.slug:
                        slug = slugify(self.title)
                        duplicate_count = Entry.objects.filter(slug__startswith = slug).count()
                        if duplicate_count:
                                slug = slug + str(duplicate_count)
                        self.slug = slug
                super(Entry, self).save(*args, **kwargs)

        class Meta:
                verbose_name = "Entry"
                verbose_name_plural = "Entries"

Any guidance?

Answer 1

The django doc on it is here: Reverse generic relations. Basically on the Blog model itself you can add a GenericRelation…

class Blog(models.Model):
    favorites = generic.GenericRelation(Favorite)

For a given blog you can find all of the Favorite models that are associated with it…

b = Blog.objects.get(slug='hello-world-blog-slug')
all_blog_favorites = b.favorites.objects.all()

Or see if the current user has the blog favorited…

user_has_blog_favorited = b.favorites.objects.filter(user=request.user).exists()