assert hasattr(self, 'initial_data'), ( 'Cannot call `.is_valid()` as no `data=` keyword argument was ' 'passed when instantiating the serializer instance.' ) hasattr(self, 'initial_data')为真,则ok,为假,则抛出AssertionError 内容为后面的信息 hasattr(对象,属性或方法) self是本类…