Django 模板 - 是否有一种内置方法可以将当前日期作为“date"类型而不是“str"类型获取? [英] Django template - Is there a built-in way to get current date as type 'date' instead of type 'str'?

问题描述

我知道我可以在 Django 模板中以 str 的形式获取当前日期(使用 模板标签now)，像这样:

I know I can get the current date as a str in a Django template (using the template tag now), like this:

{% now "Y-m-d" as today_str %}
<p>{{ today_str }}</p>

但我不能将其用于比较:

But I cannot use that for comparissons:

{% now "Y-m-d" as today_str %}

{% for elem in object_list %}
    {% if elem.date < today_str %}        {# WRONG: this compares 'date' and 'str' #}
        <p>{{ elem.pk }} before today</p>
        {# do some other rendering #}
    {% endif %}
{% endfor %}

<小时>

可能的解决方案:

---

Possible solutions:

1. 我知道我可以将上下文变量传递给模板，但在我看来它需要代码:

1. I know I can pass a context variable to the template, but it requires code in my view:

# in my class-based-view in 'views.py'
def get_context_data(self, **kwargs):
    ctx = super().get_context_data(**kwargs)
    ctx['today'] = timezone.now()
    return ctx

或者我可以创建一个自定义模板标签，但这需要更多的额外代码.

Or I can create a custom template tag, but that is even more additional code.

正如你所看到的，我有解决我的问题的方法，但我想知道是否有一种内置方式来获取当前的date(或datetime) 在模板中?

As you can see I have workarounds for my problem, but I would like to know if there is a buit-in way to get the current date (or datetime) in the template?

推荐答案

所以，我所有的搜索都没有找到一个简短的解决方案.问题的答案似乎是:不，没有内置方法可以将当前日期(或日期时间)作为模板中的变量.

So, all my searching didn't yield a short solution. The answer to the question seems to be: no, there is no buit-in way to get the current date (or datetime) as a variable in the template.

如果其他人正在搜索此主题，我将尝试总结我可以提出的以及其他用户建议的可能解决方法.

In case others are searching for this topic, I'll try to give a summary of the possible workarounds that I can up with and that were suggested by other users.

1. 我可以从我的视图中将上下文变量传递给模板.在看起来像这样的基于类的视图中(它甚至是 文档):

 # file 'my_app/views.py'
 from django.utils import timezone as tz
 from django.views.generic import ListView

 class MyView(ListView)
     ...

     def get_context_data(self, **kwargs):
         ctx = super().get_context_data(**kwargs)

         now = tz.now()
         ctx['now'] = now
         ctx['today'] = tz.localtime(now).date()

         return ctx

我可以创建一个自定义的上下文处理器 将该变量加载到每个模板.在可能如下所示的基于类的视图中:

I could create a custom context processor that loads that variable to every template. In class-based views that could look like this:

 # file 'context_processors.py'
 from django.utils import timezone as tz

 def now_and_today(request):
     now = tz.now()
     return {
         'now': now,
         'today': tz.localtime(now).date(),
     }

 # file 'settings.py'
 ...
 TEMPLATES = [
     {
         ...
         'OPTIONS': {
             'context_processors': [
                 ...
                 'context_processors.now_and_today',
             ],
         },
     },
 ]
 ...

我可以创建一个 自定义模板标签，像这样:

 # file 'my_app/custom_template_tags/custom_time_tags.py'
 from django.utils import timezone as tz
 from django import template
 register = template.Library()

 @register.simple_tag
 def get_now(request):
     return tz.now()

 @register.simple_tag
 def get_today(request):
     return tz.localtime(tz.now()).date()

像这样使用:

 {% load 'custom_time_tags' %}

 {% get_today as today %}
 {% for per in person_list %}
     {% if per.brith_date > today %}
         <p>{{ per.name }} is from the future!!<p>
     {% endif %}
 {% endfor %}

我还可以添加一个属性(甚至是 cached_property) 到模型:

 # file 'models.py'
 from django.db import models
 from django.utils import timezone as tz
 from django.utils.functional import cached_property

 class Person(models.Model):
     ...

     @cached_property
     def is_from_future(self):
         # careful: for long-lived instances do not use 'cached_property' as
         # the time of 'now' might not be right later
         if self.birth_date > tz.localtime(tz.now()).date():
             return True

         return False

最后但并非最不重要的是，我可以在视图中进行处理并向元素添加属性:

And last but not least, I could just do the processing in the view and add a property to the elements:

 # file 'my_app/views.py'
 from django.utils import timezone as tz

 def person_list(request):
     today = tz.localtime(tz.now()).date()

     person_list = []
     for p in Person.objects.all():
         p.is_from_future = self.birth_date > today
         person_list.append(p)

     return render(request, 'some_template.html', {'person_list': person_list})

这篇关于Django 模板 - 是否有一种内置方法可以将当前日期作为“date"类型而不是“str"类型获取?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！