django返回记录的最新日期 [英] django return the most recent date of a record

问题描述

我正在尝试从用户的许多记录中返回最近的日期.

I am trying to return the most recent date from a number of records by a user.

用户创建文档时，创建日期存储在CreatedDocumentDetails模型中.

When the user creates a document, the date created is stored in the CreatedDocumentDetails model.

我无法返回用户最近创建的文档的日期.

I am unable to return the date of the most recently created document by the user.

我问了关于SO的问题与该问题有关.

这是我的model.py代码:

Here is my model.py code:

class CreatedDocumentDetails(models.Model):
    user = models.ForeignKey(User)
    created_document_timestamp = models.DateTimeField(auto_now_add=True, blank=True)

    def __unicode__(self):
        return unicode(self.user)

这是我的views.py代码:

Here is my views.py code:

def get_latest_created_document_date(user):
    ??
    return latest_created_document_date

我了解我必须在用户的get_latest_created_document_date视图的过滤器中传递日期，但是在搜索SO，Google和Django文档之后，我仍然无法自行解决该问题.

I understand I have to pass the date in the filter of the get_latest_created_document_date view of the user, but after searching SO, Google and Django docs, I am still unable to figure this out on my own.

推荐答案

您将要使用

You'll want to use the order_by QuerySet filter, like so:

CreatedDocumentDetails.objects.order_by('-created_document_timestamp').first()

由于您使用的是日期字段，因此您也可以使用最新过滤器，如下所示:

Since you are using a date field, you can also use the latest filter like so:

CreatedDocumentDetails.objects.latest('created_document_timestamp')

如Catavaran在评论中所述

As catavaran states in the comments

请注意，如果表中没有记录，则 first()将返回 None ，但 latest()将引发 DoesNotExist例外

要获取日期戳，您可以将字段追加到末尾，因为两个查询都将给出一个对象:

To just get the datestamp, you can append the field to the end, as both queries will give a single object:

CreatedDocumentDetails.objects.order_by('-created_document_timestamp').first().created_document_timestamp 

或

CreatedDocumentDetails.objects.latest('created_document_timestamp').created_document_timestamp

这篇关于django返回记录的最新日期的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！