Question

我想首先按 NoteReposter 模型（中介）的 date_added （日期时间）对备注对象进行排序，如果是的话null然后按注意模型本身的 date_created （DateTime）对其进行排序。

这是我目前在views.py

中所做的工作

class Note(models.Model):
    note = models.CharField(max_length=2100)
    date_modified = models.DateTimeField(auto_now=True, blank=True)

    # If the notereposter__date_added is null then sort it using this datetime field
    date_created = models.DateTimeField(auto_now_add=True)

    author = models.ForeignKey('NotepikUser',
        related_name="%(class)ss_created")

    reposters = models.ManyToManyField('NotepikUser', through="NoteReposter", 
        related_name="%(class)ss_reposted", blank=True)

    categories = models.ManyToManyField('Category', blank=True, 
        related_name='notes')

在我的models.py

中

注意型号

class NoteReposter(models.Model):
    note = models.ForeignKey("Note", on_delete=models.CASCADE)
    user = models.ForeignKey("NotepikUser", on_delete=models.CASCADE)
    date_modified = models.DateTimeField(auto_now=True, blank=True)

    # Sort by this datetime field first
    date_added = models.DateTimeField(auto_now_add=True)

NoteReposter模型（中介）

someone created note1 (Note)
note1 date_created is 2016 January 1, 5:00 PM

User2 created note2
note2 date_created is 2016 January 1, 5:30 PM

User2 reposted note1 (note of someone)
notereposter1 (NoteReposter instance) created with user = User2,
             note=note1, date_added = 2016 January 1, 6:00 PM

User2 created note3
note3 date_created is 2016 January 1, 6:30 PM

不幸的是我的解决方案没有正确排序

谢谢！

修改

<note3> 6:30 PM,
<notereposter1.note> 6:00pm 
<note2> 5:30pm

我希望这些笔记按照这样排序

{{1}}

Answer 1

我现在明白了。对于那些感兴趣的人，这是我的解决方案。

from django.db.models import DateTimeField, F, Case, When
notes.annotate(newest_in_vault=Case(When(notereposter__isnull=False,
        then=F("notereposter__date_added")), default=F("date_created"),
        output_field=DateTimeField()))
# Sort it now
notes = notes.order_by("-newest_in_vault")

Django：按许多模型的日期时间和模型本身的日期时间排序

1 个答案: