[英]How to persist and load all attributes of a dataclass
I want to persist all attributes of an object which is an instance of a dataclass.我想保留 object 的所有属性,它是数据类的一个实例。 Then I want to load back that object from the files that I persisted.然后我想从我保留的文件中加载回 object。
Here it is an example that fullfills the task:这是一个完成任务的例子:
from dataclasses import dataclass
import pickle
@dataclass
class Circle:
radius: float
centre: tuple
def save(self, path: str):
name = ".".join(("radius", "pkl"))
with open("/".join((path, name)), "wb") as f:
pickle.dump(self.radius, f)
name = ".".join(("centre", "pkl"))
with open("/".join((path, name)), "wb") as f:
pickle.dump(self.centre, f)
@classmethod
def load(cls, path):
my_model = {}
name = "radius"
file_name = ".".join((name, "pkl"))
with open("\\".join((path, file_name)), "rb") as f:
my_model[name] = pickle.load(f)
name = "centre"
file_name = ".".join((name, "pkl"))
with open("\\".join((path, file_name)), "rb") as f:
my_model[name] = pickle.load(f)
return cls(**my_model)
>>> c = Circle(2, (0, 0))
>>> c.save(r".\Circle")
>>> c_loaded = Circle.load(r".\Circle")
>>> c_loaded == c
True
As you can see I need to repeat the same code for every attribute, what is a better way to do it?如您所见,我需要为每个属性重复相同的代码,更好的方法是什么?
In the save method it use self.__dict__
.在保存方法中,它使用self.__dict__
。 That contains all attribute names and values as a dictionary.它包含作为字典的所有属性名称和值。 Load is a classmethod so there is no __dict__
at that stage. Load 是一个类方法,所以在那个阶段没有__dict__
。 However, cls.__annotations__
contains attribute names and types, still stored in a dictionary.但是, cls.__annotations__
包含属性名称和类型,仍然存储在字典中。
Here it is the end result:这是最终结果:
from dataclasses import dataclass
import pickle
@dataclass
class Circle:
radius: float
centre: tuple
def save(self, path):
for name, attribute in self.__dict__.items():
name = ".".join((name, "pkl"))
with open("/".join((path, name)), "wb") as f:
pickle.dump(attribute, f)
@classmethod
def load(cls, path):
my_model = {}
for name in cls.__annotations__:
file_name = ".".join((name, "pkl"))
with open("/".join((path, file_name)), "rb") as f:
my_model[name] = pickle.load(f)
return cls(**my_model)
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