Django - 获取创建的最后一个对象，同时过滤器 [英] Django - Getting last object created, simultaneous filters
问题描述
抱歉，我对 Django 和 Python 完全陌生.
Apologies, I am completely new to Django and Python.
我有两个问题.首先，我将如何获取对象列表中创建的最后一个对象(或最高 pk)?例如，我知道我可以使用以下内容来获取第一个对象:
I have 2 questions. First, how would I go about getting the last object created (or highest pk) in a list of objects? For example, I know that I could use the following to get the first object:
list = List.objects.all()[0]
有没有办法获取List.objects的长度?我试过 List.objects.length 但无济于事.
Is there a way to get the length of List.objects? I've tried List.objects.length but to no avail.
第二，是否可以同时创建过滤器或组合列表?下面是一个例子:
Second, is it possible to create simultaneous filters or combine lists? Here is an example:
def findNumber(request, number)
phone_list = Numbers.objects.filter(cell=number)
我想要类似上面的东西，但更像:
I want something like the above, but more like:
def findNumber(request, number)
phone_list = Numbers.objects.filter(cell=number or home_phone=number)
如果有的话，正确的语法是什么?
What is the correct syntax, if any?
推荐答案
我还没试过，但我会看看 latest() 运算符在 查询集:
I haven't tried this yet, but I'd look at the latest() operator on QuerySets:
最新的(field_name=None)
latest(field_name=None)
返回最新的对象表，按日期，使用 field_name作为日期字段提供.
Returns the latest object in the table, by date, using the field_name provided as the date field.
这个例子返回最新的Entry在表中，根据pub_date 字段:
This example returns the latest Entry in the table, according to the pub_date field:
Entry.objects.latest('pub_date')
Entry.objects.latest('pub_date')
如果您的模型的 Meta 指定get_latest_by，你可以不使用给latest() 的field_name 参数.Django 将使用中指定的字段默认为 get_latest_by.
If your model's Meta specifies get_latest_by, you can leave off the field_name argument to latest(). Django will use the field specified in get_latest_by by default.
像 get(), latest() 引发如果对象不存在，则DoesNotExist以给定的参数存在.
Like get(), latest() raises DoesNotExist if an object doesn't exist with the given parameters.
注意 latest() 纯粹是为了便利性和可读性.
Note latest() exists purely for convenience and readability.
以及关于 get_latest_by 的 模型文档:
And the model docs on get_latest_by:
get_latest_by
get_latest_by
Options.get_latest_by
Options.get_latest_by
模型中 DateField 或 DateTimeField 的名称.这指定了在模型 Manager 的最新方法中使用的默认字段.
The name of a DateField or DateTimeField in the model. This specifies the default field to use in your model Manager's latest method.
示例:
get_latest_by = "order_date"
get_latest_by = "order_date"
有关更多信息，请参阅 latest() 的文档.
See the docs for latest() for more.
Wade 对 Q() 运算符有很好的回答.
Wade has a good answer on Q() operator.
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