多个对象在pickle文件中

Question

我想把多个对象保存到一个pickle文件里，并且以后能把它们取出来。现在我已经能保存对象了，但当我加载文件的时候，只能加载到最后一个对象。我哪里出错了呢？

import pickle

class People():
    def __init__(self, name, surname, age, mobile_no, home_no):
        self.name = name
        self.surname = surname
        self.age = age
        self.mobile_no = mobile_no
        self.home_no = home_no

    def DisplayContacts(self):
        print("First Name: \t", self.name)
        print("Surname: \t", self.surname)
        print("Age: \t", self.age)
        print("Mobile Number: \t", self.mobile_no)
        print("Home Number: \t", self.home_no)
        print()


def addContact():
    newname = str(input("First name: \t"))
    newsurname = str(input("Surname: \t"))
    newage = int(input("Age: \t"))
    newmobile_no = int(input("Mobile Number: \t"))
    newhome_no = int(input("Home Number: \t"))
    newContact = People(newname, newsurname, newage, newmobile_no, newhome_no) 
    return newContact

cont = 1

contacts = []


while cont == 1:
    user = input("Do you want to add contact? (Y/N)")
    if user == "Y" or user == "y":
        print ("works")
        contacts.append(addContact())
        file = open("List.pickle", "wb")
        pickle.dump(contacts, file, pickle.HIGHEST_PROTOCOL)
        file.close()
    else:
        print ("111")
        cont = 0

useropen = input("open file? (Y/N)")
if useropen == "Y" or useropen == "y":
    with open ("List.pickle", "rb") as pickled_file:
        contacts = pickle.load(pickled_file)
else:
    print("Null")

现在看起来，当我尝试加载文件时，它是空的：

import pickle

class People():
    def __init__(self, name, surname, age, mobile_no, home_no):
        self.name = name
        self.surname = surname
        self.age = age
        self.mobile_no = mobile_no
        self.home_no = home_no

    def DisplayContacts(self):
        print("First Name: \t", self.name)
        print("Surname: \t", self.surname)
        print("Age: \t", self.age)
        print("Mobile Number: \t", self.mobile_no)
        print("Home Number: \t", self.home_no)
        print()


def addContact():
    newname = str(input("First name: \t"))
    newsurname = str(input("Surname: \t"))
    newage = int(input("Age: \t"))
    newmobile_no = int(input("Mobile Number: \t"))
    newhome_no = int(input("Home Number: \t"))
    newContact = People(newname, newsurname, newage, newmobile_no, newhome_no) 
    return newContact

cont = 1

contacts = []


while cont == 1:
    user = input("Do you want to add contact? (Y/N)")
    if user == "Y" or user == "y":
        print ("works")
        contacts.append(addContact())
        file = open("CList.pickle", "ab")
        pickle.dump(contacts, file, pickle.HIGHEST_PROTOCOL)
        file.close()
    else:
        print ("111")
        cont = 0

useropen = input("open file? (Y/N)")
if useropen == "Y" or useropen == "y":

    with open ("CList.pickle", "rb") as pickled_file:
        contacts = pickle.load(pickled_file)
else:
    print("Null")

Answer 1

补充一下@Ethan Furman说的内容，'b'在Windows和Unix系统中的功能似乎有些不同（参考链接）。你的代码在Unix系统上可能运行得很好，但在Windows操作系统上可能会出现截断的问题。

Answer 2

你在每次循环的时候都在重新写你的Pickle文件，因为你是用"wb"模式打开它的。

在这个循环中，你一直在往contacts列表里添加联系人（然后每次循环都把这个列表的一个新副本保存下来——这可能不是你想要的效果）。我建议你把保存Pickle文件的那部分代码移到while循环之后，只保存一次完整的联系人列表，这样就不需要保存多个对象了。

Answer 3

你现在用 wb 模式打开你的 pickle 文件，这个模式会把文件清空，然后再写入新的内容。你其实应该用 a 模式，这个模式是用来在文件末尾添加内容的。