django signals 信号
配置方式
app下的 __init__.py
default_app_config="web.apps.WebConfig"
#初始化app配置
#调用app下面的类
同一个app下的 apps.py
from django.apps import AppConfig #导入 #app配置
class WebConfig(AppConfig): #必须继承这个类
name = 'web' #app def ready(self):
import web.signals.trade_signal
import web.signals.study_signal
import web.signals.notice_signal
信号
from django.db.models.signals import post_save #保存后 from django.db.models.signals import pre_save #保存前 from django.dispatch import receiver #使用信号的装饰器 检测Django 模型对象字段值的变化 from web import models #数据库
orm操作前触发
@receiver(pre_save, sender=models.Order)
def get_order_status(sender, instance=None, **kwargs):
"""
获取订单状态
:param sender:
:param instance: #当前对象
:param kwargs:
:return:
"""
#对象保存前
orm操作后触发
@receiver(post_save, sender=models.Order)
def create_enrolled_record(sender, instance=None, created=False, **kwargs):
"""
:param sender:
:param instance:保存后的对象
:param created: 是否是创建新的记录
:param kwargs:
:return:
"""
#保存对象后
signals.py
import warnings
from functools import partial from django.db.models.utils import make_model_tuple
from django.dispatch import Signal
from django.utils import six
from django.utils.deprecation import RemovedInDjango20Warning class_prepared = Signal(providing_args=["class"]) class ModelSignal(Signal):
"""
Signal subclass that allows the sender to be lazily specified as a string
of the `app_label.ModelName` form.
"""
def _lazy_method(self, method, apps, receiver, sender, **kwargs):
from django.db.models.options import Options # This partial takes a single optional argument named "sender".
partial_method = partial(method, receiver, **kwargs)
if isinstance(sender, six.string_types):
apps = apps or Options.default_apps
apps.lazy_model_operation(partial_method, make_model_tuple(sender))
else:
return partial_method(sender) def connect(self, receiver, sender=None, weak=True, dispatch_uid=None, apps=None):
self._lazy_method(
super(ModelSignal, self).connect, apps, receiver, sender,
weak=weak, dispatch_uid=dispatch_uid,
) def disconnect(self, receiver=None, sender=None, weak=None, dispatch_uid=None, apps=None):
if weak is not None:
warnings.warn("Passing `weak` to disconnect has no effect.", RemovedInDjango20Warning, stacklevel=2)
return self._lazy_method(
super(ModelSignal, self).disconnect, apps, receiver, sender, dispatch_uid=dispatch_uid
) pre_init = ModelSignal(providing_args=["instance", "args", "kwargs"], use_caching=True)
post_init = ModelSignal(providing_args=["instance"], use_caching=True) pre_save = ModelSignal(providing_args=["instance", "raw", "using", "update_fields"],
use_caching=True)
post_save = ModelSignal(providing_args=["instance", "raw", "created", "using", "update_fields"], use_caching=True) pre_delete = ModelSignal(providing_args=["instance", "using"], use_caching=True)
post_delete = ModelSignal(providing_args=["instance", "using"], use_caching=True) m2m_changed = ModelSignal(
providing_args=["action", "instance", "reverse", "model", "pk_set", "using"],
use_caching=True,
) pre_migrate = Signal(providing_args=["app_config", "verbosity", "interactive", "using", "apps", "plan"])
post_migrate = Signal(providing_args=["app_config", "verbosity", "interactive", "using", "apps", "plan"])