Django Caching Notes

gistfile1.txt

- Cache One Object (Active Homepage Layout)
    by_pk or by_* (any field) 
    lazy queryset methods (loaded and cached when first used)
    warm queryset methods (preloaded by warming)

- Cache Entire Table (Categories)
    load entire table into in-memory hash, indexes on pk and slug
    .cached manager for loading from cached, use_for_related=True

- Cache Busy Queries (Page 1 of Story List by Category)
    pre-warmed, never expire
    when invalidated, re-warm instead of flush

- Cache HTML (Template Tag)
    template chunk (homepage optimization)

models.py

class Homepage(cachemodels.CacheModel):
    is_active = models.BooleanField()
    name = models.CharField()

    @cachemodels.cached_method
    def featured_books(self):
        return self.homepagebook_set.all()


class HomepageBook(cachemodels.CacheModel):
    homepage = models.ForeignKey(Homepage)
    book = models.ForeignKey(Book)


class Category(cachemodels.CachedTable):
    name = models.CharField()
    slug = models.SlugField()


class Author(cachemodels.CacheModel):
    name = models.CharField()
    bio = models.TextField()


class BookManager(cachemodels.CacheModelManager):
    @cachemodels.cached_query
    def cached_listings(self, category=None, page=1, limit=10):
        qs = self.all()
        if category:
            qs.filter(category=category)
        offset = (page-1)*limit
        return qs[offset:offset+limit]

    @cachemodels.cached_query
    def popular(self, limit=5):
        return self.filter(is_active=True).order_by('-denorm_popularity')[:limit]


class Book(cachemodels.CacheModel):
    is_active = models.BooleanField()
    slug = models.SlugField()
    name = models.CharField()
    author = models.ForeignKey(Author)
    category = models.ForeignKey(Category)
    denorm_popularity = models.IntegerField()

    @cachemodels.cached_method
    def related_books(self, how_many=5):
        return Book.objects.filter(category=self.category)

    @cachemodels.denormalized_field('denorm_popularity')
    def popularity(self):
        return Comment.objects.filter(book=self).count()





class Comment(cachemodels.CacheModel):
    book = models.ForeignKey(Book)
    body = models.TextField()

templatesbookdetail.html

<h2>{{book.name}}</h2>
<h3>{{book.author}}</h3>

<ul>
{%for related in book.related_books%}
    <li>
        <img src="{{related.cover}}"/>
        <p>{{related.name}}</p>
        <p class="author">{{related.author}}</p>
        <p>{{related.category}}</p>
    </li>
{%endfor%}
</ul>

views.py

def book_detail(request, book_slug):
    book = Book.objects.get_by_slug(book_slug)
    return render_template(request, 'book/detail.html', {'book': book})


def book_listing(request, category=None):
    books = Book.objects.cached_listings(category=category, page=request.GET.get('page','1'))
    return render_template(request, 'book/listing.html', {'books': books})