Django ORM条件过滤器 [英] Django ORM conditional filter LIKE CASE WHEN THEN

问题描述

我正在使用Django 1.11，Postgresql 9.2，python 3.4

I'm using Django 1.11, Postgresql 9.2, python 3.4

如果事件类型为单个，我想基于名为event_type的表的列选择数据，然后比较应该为同一日期(今天)的日期，否则选择给定的所有日期(今天)该类型为重复发生的日期.

I want to select data based on table's column named event_type if event type is single then compare date that should be of same date (today's) date else select all dates of given (today's) date that type would be of recurring.

但是我们不能使用单个查询来管理它吗?就像我们在汇总中执行CASE和WHEN，THEN一样吗?我尝试使用Q对象，但没有运气. 我想检查值何时为单个"，然后添加条件，否则为另一个条件.

But can't we manage this using single query? Like we do CASE and WHEN, THEN in Aggregation? I tried using Q object but no luck. I want to check when value is 'single' then add condition, else another condition.

我找不到任何好的解决方案，目前我已经使用

I could not find any good solution, currently I've achieved using this

today = datetime.date.today().strftime('%Y-%m-%d')
single_events = crm_models.EventsMeta.objects.filter(
    event_type == "single",
    repeat_start=today
)

recurring_events = crm_models.EventsMeta.objects.filter(
    event_type == "recurring"
    repeat_start__lte=today
)

all_events = single_events | recurring_events

有关更多信息，我的模型是:

For more information my model is:

class EventsMeta(models.Model):
    event_type = models.CharField(max_length=50, choices=(("single","Single"),("recurring","Recurring")), 
                            null=False, blank=False,default='single',verbose_name="Event Type")
    repeat_start = models.DateTimeField()
    repeat_end = models.DateTimeField()

推荐答案

您可以将许多带有()符号的Q对象组合在一起.如果您的情况适合我，我想这是可行的:

You can combine many Q objects with () signs. I your case I suppose this will work:

single_events = crm_models.EventsMeta.objects.filter(
    (Q(event_type="single") & Q(repeat_start=today)) |
    (Q(event_type="recurring") & Q(repeat_start__lte=today))
)

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