无法从文件中加载泡菜对象 [英] Unable to load pickle object from file

问题描述

我只是尝试使用pickle模块并学习其功能和实用程序.我已经写了这小段代码，但这给我带来了麻烦.

I'm just trying out the pickle module and learning its functions and utilities. I've written this small piece of code, but it's giving me trouble.

import pickle
myfile = open("C:\\Users\\The Folder\\databin.txt", 'r+') #databin.txt is completely blank
class A:
    def __init__ (self):
        self.variable = 25
        self.random = 55
pickle.dump (A, myfile, -1) #HIGHEST_PROTOCOL 
pickle.load (myfile)

然后我得到以下错误:

 Traceback (most recent call last):
File "<pyshell#9>", line 1, in <module>
pickle.load (myfile)
File "C:\Python27\lib\pickle.py", line 1378, in load
return Unpickler(file).load()
File "C:\Python27\lib\pickle.py", line 858, in load
dispatch[key](self)
KeyError: '\x00'

推荐答案

您需要先关闭文件，然后重新打开文件才能正常工作；并使用二进制模式打开文件.

You'd need to close the file first, then reopen it for that to work; and use binary mode to open your file.

最后但并非最不重要的是，泡菜只能存储类的实例，而不能存储类本身:

Last but not least, pickle can store instances of classes only, not the classes themselves:

filename = "C:\\Users\\The Folder\\databin.txt"
with open(filename, 'wb') as myfile:
    pickle.dump(A(), myfile, -1) #HIGHEST_PROTOCOL 
with open(filename, 'rb') as myfile:
    pickle.load(myfile)

在这里，我已将该文件用作上下文管理器，当with套件退出时，它将自动关闭.

Here I've used the file as a context manager, it'll close automatically when the with suite is exited.

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