python - 如何使用 Django 创建特定的 if 条件模板标签？

Question

我的问题是 if 条件。

我想要那样的东西，但不知道该怎么做。

{% if restaurant.is_favorite_of(user) %}
     <img src="{{MEDIA_URL}}images/favorite_on.png" alt="This restaurant is one of your favorite (Click to undo)" />
{% else %}
     <img src="{{MEDIA_URL}}images/favorite_off.png" alt="This restaurant is not one of your favorite (Click to add to your favorite)" />
{% endif %}

在收藏夹管理器中，我创建了:

def is_favorite(self, user, content_object):
    """
    This method returns :
       - True if content_object is favorite of user
       - False if not
    >>> user = User.objects.get(username="alice")
    >>> fav_user = User.objects.get(username="bob")
    >>> fav1 = Favorite.create_favorite(user, fav_user)
    >>> Favorite.objects.is_favorite(user, fav_user)
    True
    >>> Favorite.objects.is_favorite(user, user)
    False
    >>> Favorite.objects.all().delete()

    Above if we test if bob is favorite of alice it is true.
    But alice is not favorite of alice.
    """
    ct = ContentType.objects.get_for_model(type(content_object))
    try:
        self.filter(user=user).filter(content_type = ct).get(object_id = content_object.id)
        return True
    except Favorite.DoesNotExist:
        return False

因为在 Django 模板中没有办法这样做，我可以做一个像这样的模板标签:

{% is_favorite user resto %}
     <img src="{{MEDIA_URL}}images/favorite_on.png" alt="This restaurant is one of your favorite (Click to undo)" />
{% else %}
     <img src="{{MEDIA_URL}}images/favorite_off.png" alt="This restaurant is not one of your favorite (Click to add to your favorite)" />
{% endif %}

但是怎么做呢？ 你有更好的主意吗？

Answer 1

最简单的方法是创建一个过滤器。

@register.filter
def is_favourite_of(object, user):
    return Favourite.objects.is_favourite(user, object)

在模板中:

{% if restaurant|is_favourite_of:user %}