4

I've setup a system to track moderation tasks for various objects in the database. These are linked via a Generic Foreign Key relation. Given a ObjectModerationState Object I must determine its state from the most recent StateTransisition object.

The solution must lend it self to be used in a SimpleListFilter for sorting on list_display using list_filter.

e.g. Given States - Queued - Completed - Verify

I should be able to filter ObjectModerationState Objects, based on the latest state value in the StateTransisition object.

I've been leaning towards some sort of annotation on the ObjectModerationState.

Here's what I have that isn't working.

models.py:

class ObjectModerationState(models.Model):
    job = models.ForeignKey(JobDescription)
    object_id = models.TextField(help_text="Primary key of the model under moderation.")
    content_type = models.ForeignKey(ContentType, help_text="Content type of the model under moderation.")
    object = generic.GenericForeignKey()

class StateTransisition(models.Model):
    state = models.ForeignKey(State)
    moderation_details = models.ForeignKey("ObjectModerationState", related_name='states')
    changed_by = models.ForeignKey("auth.User", related_name='+', null=False,
                                   help_text="If you create the task, then usually this will be you.")
    date_updated = models.DateTimeField(_("Date Set"))
    last_modified = models.DateTimeField(auto_now=True)


    def __unicode__(self):
        return "%s in state %s by %s" % (self.moderation_details.object, self.state, self.changed_by)

    class Meta:
        ordering = ['last_modified', ]
        get_latest_by = 'last_modified'

class State(Orderable):
    label = models.CharField(_("State Label"), max_length=100, unique=True)
    description = models.TextField(_("Description"), max_length=200, null=True, blank=True,
                                   help_text=_("Explination of this state in context"))
    valid_transitions = models.ManyToManyField("State", null=True, blank=True,
                                               help_text=_("You must add these mappings."))

    def __unicode__(self):
        return "%s" % (self.label)

    class Meta:
        abstract = False

admin.py

class CurrentStateFilter(SimpleListFilter):
    title = 'current state'
    parameter_name = 'current state'

    def lookups(self, request, model_admin):
        states = State.objects.all()
        return  [(c.id, c) for c in states]

    def queryset(self, request, queryset):
        if self.value():
            queryset.filter(states__state__id=self.value()) <<< ????
        else:
            return queryset

EDIT

4

2 回答 2

6

对于这种情况，缓存绝对是一个好方法。然而，为了完整起见，我想证明我已经能够使用以下 Django ORM 查询做同样的事情：

EventGroup.objects.annotate(
    latest_event_date=Max('events__timestamp')
).filter(
    events__timestamp=F('latest_event_date'),
    events__state=EventState.STATE_PROCESSED,
)

因此，对于每个EventGroup，都被注释为该组事件latest_event_date的最大值。timestamp此外，我过滤以仅包含EventGroup最新事件状态为 的 s EventState.STATE_PROCESSED。

我相当肯定这样的事情会在你的情况下工作。

于 2017-06-24T20:38:01.157 回答
1

经过大量研究，我不确定它是否可以在没有非常hacky的情况下完成。我最终将值直接缓存在 list_display 中显示的模型上。我使用后保存信号做到了这一点。它工作得很好。

于 2013-05-14T02:38:40.273 回答