模型相关
pre_init = ModelSignal(providing_args=["instance", "args", "kwargs"], use_caching=True) # 对象初始化前...(providing_args=["instance", "raw", "using", "update_fields"],
use_caching=True...m2m_changed = ModelSignal(
providing_args=["action", "instance", "reverse", "model", "pk_set",...", "verbosity", "interactive", "using", "apps", "plan"]) #数据迁移前
post_migrate = Signal(providing_args...=["request"]) #request 请求出错后
setting_changed = Signal(providing_args=["setting", "value", "enter"])