组合和排序查询集

Question

我正在尝试将额外的模型添加到有序的项目列表中，并让列表中的所有内容按每个模型上的日期字段排序。

我想我已经通过链接每个查询集并用一个键对它们进行排序来破解了它；

def get_ordering(obj):
    """
    Helper to get the 'order_by' field for the paginated latest news list.
    :param obj: Object used in the paginated latest news
    :type obj: django.db.model
    :return: ordering field
    :rtype: str
    """
    if isinstance(obj, LatestNews):
        return '-publish_date'
    else:
        return '-date_created'


def build_paginated_latest_news(request, instance=None, placeholder=None):

    paginated_page_no = get_page_no(request)
    paginated_page_items = get_page_items(request)
    latest_news = LatestNews.cached.published_items(
        request, instance, placeholder
    )
    query = published_items(request)
    videos = VideoGalleryPlugin.objects.filter(query)
    audio = Audio.objects.filter(query)

    obj_list = sorted(
        chain(latest_news, videos, audio),
        key=lambda instance: get_ordering(instance)
    )
    paginator = Paginator(obj_list, paginated_page_items)

但最终呈现的列表显示为视频、音频，latest_news 这甚至不是我将它们链接在一起的顺序。

将这样的键与 sorted() 结合查询集是否正确？

Answer 1

在 get_ordering() 中，您应该 return 排序函数将使用的值：

def get_ordering(obj):
    if isinstance(obj, LatestNews):
        return obj.publish_date
    else:
        return obj.date_created

然后在你看来：

obj_list = sorted(
    chain(latest_news, videos, audio),
    key=get_ordering, # intermediate lambda is not needed here
    reverse=True
)

组合和排序查询集

Combining & ordering querysets

python

django

django-queryset