python中特定格式的日期范围

我必须在python中输入开始日期和结束日期。 我的要求是我想要以下提到的格式的日期范围

from datetime import datetime, timedelta

a = 'yesterday' # I don't want to hardcore the date value
b = '7daysAgo'
start_date = a 00:00:00
end_date = b 23:59:59

小时分和秒分应该是相同的，无论何时我使用代码，它都不会受到影响。

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请根据问题提出建议，我不确定您想要的是采用该格式的日期对象，还是采用问题中所述格式的字符串： 格式化字符串：

from datetime import datetime, timedelta

yesterday = datetime.now() - timedelta(days=1)
yesterday = yesterday.strftime('%Y-%m-%d 00:00:00')

end_date = datetime.now() - timedelta(days=7)
end_date = end_date.strftime('%Y-%m-%d 23:59:59')

日期对象

yesterday = datetime.now() - timedelta(days=1)
yesterday = yesterday.replace(hour=00, minute=00, second=00,microsecond=00)

end_date = datetime.now() - timedelta(days=7)
end_date = end_date.replace(hour=23, minute=59, second=59,microsecond=00)