当QuerySet加载实例时，Django是否发送信号pre_init/post_init？

Question

我需要在查询集加载的每个实例上调用实例方法。我可以使用pre_init/post_init信号吗？

Answer 1

是的，即使从查询集创建实例时，也会发送pre_init/post_init。

不要把我的话，试试吧例如： -

def pre_init_callback(sender, **kwargs): 
    print 'pre_init', sender, kwargs 
pre_init.connect(pre_init_callback) 

def post_init_callback(sender, **kwargs): 
    print 'post_init', sender, kwargs 
post_init.connect(post_init_callback) 

将输出类似：

In [5]: list(Profile.objects.all()) 
pre_init <class 'testapp.models.Profile'> {'signal': <django.dispatch.dispatcher.Signal object at 0x15e6450>, 'args': (1, False, None), 'kwargs': {}} 
post_init <class 'testapp.models.Profile'> {'instance': <Profile: Profile object>, 'signal': <django.dispatch.dispatcher.Signal object at 0x15e6490>} 
pre_init <class 'testapp.models.Profile'> {'signal': <django.dispatch.dispatcher.Signal object at 0x15e6450>, 'args': (2, False, None), 'kwargs': {}} 
post_init <class 'testapp.models.Profile'> {'instance': <Profile: Profile object>, 'signal': <django.dispatch.dispatcher.Signal object at 0x15e6490>} 
Out[5]: [<Profile: Profile object>, <Profile: Profile object>]