Python JSON操作报错：JSONDecodeError: Extra Data问题求助

我尝试将字典写入JSON文件，后续在代码中搜索该JSON字典的键以加载并打印关联值，但执行写入操作时持续报错。

写入数据的代码 #

password_dictionary = {}
with open('dictionary.json', 'a') as f:
    dictionary = "dictionary.json"

# 加密用户输入的密码并写入JSON文件
def encrypt_and_dump(username, password):
    e_password = password.encode('utf-8')
    encrypted = k.encrypt(e_password)
    d_encrypted = encrypted.decode('utf-8')
    a = {site: [username, d_encrypted]}
    try:
        with open(dictionary, 'r') as f:
            password_dictionary = json.load(f) 
    except FileNotFoundError:
        password_dictionary = {}
    password_dictionary.update(a)
    with open(dictionary, 'w') as f:
        json.dump(password_dictionary, f)

加载并搜索信息的代码 #

def search_and_decrypt():
        r_site = str(input("Enter the Site Name to retrieve your credentials (Password Manager is case sensitive.): "))
        with open(dictionary, 'r') as f:
            password_dictionary = json.load(f) if f.readable() else {}
        for site, user_pass in password_dictionary.items():
            if site == r_site:
                print("ACCOUNT FOUND") 
                c_password = str(pwinput.pwinput("Confirm your Password Manager password to decrypt login credentials: "))
                if c_password == m_password:
                    decrypt_user_pass = k.decrypt(user_pass)
                    print(decrypt_user_pass)
                else:
                    print("Site Account not found.")

报错信息 #

File "/Users/makaylagalbraith/Documents/Python/PasswordManager.py", line 138, in <module>
    encrypt_and_dump(username2, c_password2)
  File "/Users/makaylagalbraith/Documents/Python/PasswordManager.py", line 72, in encrypt_and_dump
    password_dictionary = json.load(f) 
  File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/json/__init__.py", line 293, in load
    return loads(fp.read(),
  File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/json/decoder.py", line 340, in decode
    raise JSONDecodeError("Extra data", s, end)
json.decoder.JSONDecodeError: Extra data: line 1 column 3 (char 2)

问题原因与修复方案 #

1. 初始文件操作损坏JSON结构 #

开头的with open('dictionary.json', 'a') as f:会创建空文件或向现有文件追加空内容，空文件不属于有效的JSON格式，后续json.load读取时直接触发解码错误。

修复：删除这段多余的代码，函数内部已包含完整的文件读写逻辑。

2. site变量未定义 #

encrypt_and_dump函数中a = {site: [username, d_encrypted]}的site未作为参数传入，会触发NameError，必须将site添加为函数参数。

3. 修复已损坏的JSON文件 #

当前dictionary.json已因错误操作变成无效JSON，需手动删除该文件，让代码首次运行时重新创建有效的JSON结构。

4. 搜索解密函数逻辑修正 #

• user_pass是包含用户名和加密密码的列表，解密时需取第二个元素，且要转回字节类型（加密时先编码为字节，解密后转字符串存储）。
• 错误提示"Site Account not found."位置错误，应放在密码验证失败场景；遍历结束后未找到站点也需给出提示。

修复后的完整代码片段 #

修复后的写入函数

import json

# 假设k和m_password是已定义的加密密钥和管理密码
def encrypt_and_dump(site, username, password):
    e_password = password.encode('utf-8')
    encrypted = k.encrypt(e_password)
    d_encrypted = encrypted.decode('utf-8')
    new_entry = {site: [username, d_encrypted]}
    
    try:
        with open('dictionary.json', 'r') as f:
            password_dictionary = json.load(f) 
    except (FileNotFoundError, json.JSONDecodeError):
        # 处理文件不存在或内容无效的情况
        password_dictionary = {}
    
    password_dictionary.update(new_entry)
    with open('dictionary.json', 'w') as f:
        json.dump(password_dictionary, f)

修复后的搜索解密函数

def search_and_decrypt():
    r_site = input("Enter the Site Name to retrieve your credentials (Password Manager is case sensitive.): ")
    try:
        with open('dictionary.json', 'r') as f:
            password_dictionary = json.load(f)
    except (FileNotFoundError, json.JSONDecodeError):
        password_dictionary = {}
    
    found = False
    for site, user_pass in password_dictionary.items():
        if site == r_site:
            found = True
            print("ACCOUNT FOUND") 
            c_password = pwinput.pwinput("Confirm your Password Manager password to decrypt login credentials: ")
            if c_password == m_password:
                # 取出加密密码字符串，转回字节后解密
                encrypted_pass = user_pass[1].encode('utf-8')
                decrypt_user_pass = k.decrypt(encrypted_pass).decode('utf-8')
                print(f"Username: {user_pass[0]}")
                print(f"Password: {decrypt_user_pass}")
            else:
                print("Incorrect manager password.")
            break
    
    if not found:
        print("Site Account not found.")

内容的提问来源于stack exchange，提问作者Makayla Galbraith