Python代码本地运行正常，嵌入PyScript时出现AttributeError错误求助

报错信息 #

Traceback (most recent call last):
File "/lib/python3.10/site-packages/_pyodide/_base.py", line 435, in eval_code
.run(globals, locals)
File "/lib/python3.10/site-packages/_pyodide/_base.py", line 304, in run
coroutine = eval(self.code, globals, locals)
File "", line 3, in
File "/home/pyodide/connection_sqlite3.py", line 45, in returnGeral
data = cursor.execute(r"SELECT * FROM tabela;")
AttributeError: 'NoneType' object has no attribute 'execute'

问题根源分析 #

1. 数据库路径与PyScript沙箱不兼容 #

本地Python运行时，data/tutorial.db是相对于脚本的路径，但PyScript运行在浏览器的Pyodide沙箱中，本地的data目录和数据库文件不会自动加载到沙箱环境，导致sqlite3.connect()调用失败，connection()函数返回None。

2. 代码逻辑错误 #

• connection()函数返回数据库连接对象，但多个函数（如returnGeral、insertData）错误地将其赋值给cursor变量，混淆了连接对象和游标对象的概念。
• 部分函数重复调用connection()创建多个独立连接，导致事务提交等操作失效；且错误处理时未明确返回值，隐式返回None。

修复方案 #

步骤1：配置数据库文件加载 #

在py-config中添加数据库文件的fetch规则，将本地数据库加载到沙箱中：

<py-config>
    [[fetch]]
    from = 'data/'
    files = ['tutorial.db'] 
    [[fetch]]
    from = 'scripts/'
    files = ['connection_sqlite3.py'] 
</py-config>

步骤2：修正代码逻辑 #

修改connection_sqlite3.py中的函数，明确区分连接与游标，添加连接检查：

修正后的完整connection_sqlite3.py

import sqlite3
from sqlite3 import Error

# 沙箱中数据库已在根目录，无需data/前缀
data = 'tutorial.db'

# 读取SQL模板文件
def templates(arquivo):
    try:
        with open(arquivo, 'r') as raw:
            edited = raw.read()
        return edited
    except Error as e:
        print(f"读取模板文件失败: {e}")
        return None

# 创建数据库连接
def connection():
    try:
        conn = sqlite3.connect(data)
        return conn
    except Error as e:
        print(f"连接数据库失败: {e}，行号14")
        return None

# 创建表
def createTable(archive):
    try:
        conn = connection()
        if not conn:
            return
        cursor = conn.cursor()
        cursor.execute(archive)
        conn.commit()
        print("表创建成功")
    except Error as e:
        print(f"创建表失败: {e}，行号23")

# 插入数据
def insertData(param):
    try:
        conn = connection()
        if not conn:
            return
        cursor = conn.cursor()
        cursor.execute(param)
        conn.commit()
        print(f"{param} 已成功插入表中" )
    except Error as e:
        print(f"插入失败: {e}，行号41")

# 查询所有数据
def returnGeral():
    try:
        conn = connection()
        if not conn:
            print("数据库连接失败，无法执行查询")
            return None
        cursor = conn.cursor()
        cursor.execute(r"SELECT * FROM tabela;")
        raw = cursor.fetchall()
        for i in raw:
            print(i)
        return raw
    except Error as e:
        print(f"查询失败: {e}，行号34")
        return None

# 执行自定义SQL
def execute(param):
    try:
        conn = connection()
        if not conn:
            return
        cursor = conn.cursor()
        cursor.execute(param)
        conn.commit()
        print(f'{param} 执行成功')
    except Error as e:
        print(f"执行失败: {e}，行号64")

步骤3：匹配项目文件结构 #

确保项目目录结构如下：

项目根目录/
├── index.html
├── data/
│   └── tutorial.db
└── scripts/
    ├── main.py
    └── connection_sqlite3.py

完整修正后的HTML代码 #

<!DOCTYPE html>
<html>
  <head>
  <meta charset="utf-8"/>
  <title>index</title>
  <link rel="stylesheet" href="https://pyscript.net/latest/pyscript.css" />
  <link rel="stylesheet" type="text/css" href="style/style.css">
  <script defer src="https://pyscript.net/latest/pyscript.js"></script>
  </head>
  <body>
    <py-config>
        [[fetch]]
        from = 'data/'
        files = ['tutorial.db'] 
        [[fetch]]
        from = 'scripts/'
        files = ['connection_sqlite3.py'] 
    </py-config>
    <py-script src="scripts/main.py"></py-script>
    <div id="principal">
        <div id="navegation">
            <input placeholder="teste" type="text">
            <button py> search </button> 
        </div>
        <div id="table">

        </div>
    </div>
  </body>
</html>

内容的提问来源于stack exchange，提问作者Recknover