如何在Django中组合自定义日期和时间字段？

Question

I'm looking for a way to combine a custom date value and a time field in django. My model only contains a time field. Now I have to annotate a new field combining a custom date and the time field. I thought the following code will solve my problem, but it only gives the date value. TimeField is ignored.

class MyModel(models.Model):
   my_time_field = TimeField()

custom_date = datetime.today().date()
objects = MyModel.objects.annotate(
    custom_datetime=Func(
        custom_date + F('my_time_field'),
        function='DATE'
    )
)

Please advise the right way to solve this issue.

Answer 1

You should be able to use a Value expression (see the docs ) in a manner similar to this:

class MyModel(models.Model):
    my_time_field = TimeField()

custom_date = datetime.today().date()
MyModel.objects.annotate(
    custom_datetime=Value(
        datetime.datetime.combine(custom_date, F('my_time_field')),
        output_field=DateTimeField()))

The key parts are to combine your custom_date , the time from your my_time_field , and then output it as a DateTimeField .

Answer 2

It was an easy solution, but took a while for me to figure it out. If anyone else having the same question, this is the answer. Just use ExpressionWrapper .

objects = MyModel.objects.annotate(
    custom_datetime=ExpressionWrapper(
        custom_date + F('my_time_field'),
        output_field=DateTimeField()
    )
)