Question

非常新手程序员，对不起，如果这是愚蠢的，或者我的英语错了。所以，我正在编写这个命令行地址簿。它由一个字典组成，该字典包含一个以键为名称变量的对象，每个对象都有与之关联的变量，如人名，电子邮件等......它有效，但现在我正在尝试使用pickle使其在内存中持久存储字典。

def create_person():
    """Adds an instance object of the Person class to the dictionary persons. persons is a global variable, that has been created previously. DATA is a variable that points to a file named test.data that exists in the same directory as the script."""
    name = raw_input("Enter the person's name here: ")
    email = raw_input("Enter the person's email here: ")    
    phone = raw_input("Enter the person's phone here: ")
    address = raw_input("Enter the person's address here: ")
    f = open(DATA, "rb")
    persons = pickle.load(f) #assign whatever is saved in the dictionary in persistent memory to global variable persons, which is empty at this point in the beginning
    f.close()
    persons[name] = Person(name, email, phone, address)    
    f = open(DATA, "wb")
    pickle.dump(persons, f)
    f.close()

但是，我收到此错误：

Traceback (most recent call last):
File "testpickle.py", line 85, in <module>
  main()
File "testpickle.py", line 40, in main
  create_person()
File "testpickle.py", line 20, in create_person
  persons = pickle.load(f)
File "/home/pedro/anaconda/lib/python2.7/pickle.py", line 1378, in load
  return Unpickler(file).load()
File "/home/pedro/anaconda/lib/python2.7/pickle.py", line 858, in load
  dispatch[key](self)
File "/home/pedro/anaconda/lib/python2.7/pickle.py", line 880, in load_eof
  raise EOFError
EOFError

我不明白这一点。我实际上已经编写了这个程序，它正在节省内存，但我意外地删除了它。发生了什么事？

Answer 1

pickle点击EOF肯定告诉文件已损坏（可能是截断的，可能是写操作失败了）。

如果你把它上传到某个地方，我们或许可以推断它到底出了什么问题。在最糟糕的情况下，你必须在里面偷看并推断出那些手动重新输入的数据。

这是您使用不可读格式而不关注其完整性的代价（例如writing to another file and only moving it over the original one after saving succeeded）。

更新：

如果您想从 new，“empty”文件开始，请在文件丢失时处理该情况并生成空dict。毕竟，文件最初应该丢失，不是吗？

空文件无效pickle数据（它必须至少包含有关对象类型的信息）。

这是处理丢失文件的“一种显而易见的方式”（（c）Python Zen）：

import errno    
try: f = open(DATA, "rb")
except IOError,e:
    if e[0]==errno.ENOENT: persons={}
    else: raise
else:
    persons = pickle.load(f)
    f.close()
    del f

Answer 2

我没有看到您的代码明显错误，但如果您只想存储这样的键/值对，您可能应该使用shelve模块而不是自制的解决方案

import shelve

persons = shelve.open(DATA)

def create_person():
    """Adds an instance object of the Person class to the dictionary persons. persons is a global variable, that has been created previously. DATA is a variable that points to a file named test.data that exists in the same directory as the script."""
    name = raw_input("Enter the person's name here: ")
    email = raw_input("Enter the person's email here: ")    
    phone = raw_input("Enter the person's phone here: ")
    address = raw_input("Enter the person's address here: ")
    persons[name] = Person(name, email, phone, address)    

while more_people:
    create_person()

persons.close()

从空的pickle文件中取消Python字典的EOFerror

2 个答案: