Question

我正在尝试设置一个信号，以便在保存有效表单时运行一个函数来执行相关任务。

我的app结构如下;

- events
    - helpers
        - __init__.py
        - status.py
    - models
        - signals
            - __init__.py
            - event.py
        - __init__.py
        - event.py
        - status.py
    - views
        - __init__.py
        - event.py

我认为信号需要在模型之前尽早导入，因此在models/__init__.py的顶部我已经from .signals import *。

# views/event.py
class AddEventView(CreateView):
    """
    View for adding an Event.
    """
    model = Event
    form_class = EventForm
    success_url = reverse_lazy('events:all_events')

    def form_valid(self, form):
        self.object = form.save()

        signals.event_status.send(
            sender=None, request=self.request, event=self.object, status=None
        ) # Should the sender be self.object?

        return super(AddEventView, self).form_valid(form)

# signals/event.py
from django.dispatch import Signal
event_status = Signal(providing_args=["request", "event", "status"])

# helpers/status.py
from ..models import Status, StatusHistory
from ..models.signals import event_status


def create_status(sender, **kwargs):
    """
    Create a status for a given event.
    """
    event = kwargs['event']
    status = kwargs['status']
    creator = User.objects.get(pk=event.creator)
    try:
        current_status = StatusHistory.objects.filter(
            event=event).order_by('timestamp')[0]
    except IndexError:
        # Not sure what we're doing here yet.
        pass
    if not status:
        status = Status.objects.get(description=_("Submitted"))

    statushistory = StatusHistory.create(
        event=event,
        event_status=status,
        user=creator
    )
    statushistory.save()

event_status.connect(create_status)

我在Pycharm中运行调试服务器，并在create_status()函数＆amp;它永远不会被击中。

我实现了这个错误吗？

Answer 1

我在一些项目中使用了信号，我总是在我的Django APP的__init__.py中导入信号（与settings.py，views.py，urls.py ...相同的文件夹）< / p>

<强> __初始化__吡啶：

import signals

<强> signals.py：

from django.db.models.signals import post_save, pre_delete 
from django.dispatch import receiver
from my_project.models import *


@receiver(post_save, sender=Modelname)  # Called after an object is saved
def create_modelname(sender, **kwargs):
    obj = kwargs['instance']  # I get the object being saved here
    # ... Here I do whatever I want

@receiver(pre_delete, sender=Modelname)  # Called before an object is deleted
def delete_modelname(sender, **kwargs):
   obj = kwargs['instance']
   # ... Do whatever you need

请记住这2次导入：

from django.db.models.signals import post_save, pre_delete
from django.dispatch import receiver

请记住导入信号

要导入您需要在项目的import signals中添加__init__.py的信号

使用此代码，当创建或删除类 Modelname 的对象时，Django会自动调用此函数。

创建对象的接收器在创建对象后被称为，被删除对象的接收器在被删除之前被称为。

Answer 2

我想您可能只需要导入helpers/status.py，例如models/__init__.py

否则你的event_status信号被定义为ok，但信号处理程序create_status永远不会被Django连接

如果您只有一个处理器用于该信号，那么将它放在与信号定义相同的模块中可能是有意义的

Answer 3

我发现一种情况，signal无法正常工作。

在某些情况下，signal（pre_save，post_save）不会发生。

Model.objects.filter(pk=pk).update(key=value)

Django信号无法正常工作

3 个答案: