Display a list of blog posts that are filtered by tag, year, month,
    author or category. Custom templates are checked for using the name
    ``blog/blog_post_list_XXX.html`` where ``XXX`` is either the
    category slug or author's username if given.

def blog_post_list(request, tag=None, year=None, month=None, username=None,
                   category=None, template="blog/blog_post_list.html",
                   extra_context=None):
    """
    Display a list of blog posts that are filtered by tag, year, month,
    author or category. Custom templates are checked for using the name
    ``blog/blog_post_list_XXX.html`` where ``XXX`` is either the
    category slug or author's username if given.
    """
    templates = []
    blog_posts = BlogPost.objects.published(for_user=request.user)
    if tag is not None:
        tag = get_object_or_404(Keyword, slug=tag)
        blog_posts = blog_posts.filter(keywords__keyword=tag)
    if year is not None:
        blog_posts = blog_posts.filter(publish_date__year=year)
        if month is not None:
            blog_posts = blog_posts.filter(publish_date__month=month)
            try:
                month = _(month_name[int(month)])
            except IndexError:
                raise Http404()
    if category is not None:
        category = get_object_or_404(BlogCategory, slug=category)
        blog_posts = blog_posts.filter(categories=category)
        templates.append(u"blog/blog_post_list_%s.html" %
                          str(category.slug))
    author = None
    if username is not None:
        author = get_object_or_404(User, username=username)
        blog_posts = blog_posts.filter(user=author)
        templates.append(u"blog/blog_post_list_%s.html" % username)

    prefetch = ("categories", "keywords__keyword")
    blog_posts = blog_posts.select_related("user").prefetch_related(*prefetch)
    blog_posts = paginate(blog_posts, request.GET.get("page", 1),
                          settings.BLOG_POST_PER_PAGE,
                          settings.MAX_PAGING_LINKS)
    context = {"blog_posts": blog_posts, "year": year, "month": month,
               "tag": tag, "category": category, "author": author}
    context.update(extra_context or {})
    templates.append(template)
    return TemplateResponse(request, templates, context)