TypeError: The view function did not return a valid response. The function either returned None 的解决

使用flask框架制作登录、注册的页面时,app.py运行成功,数据库有用户,1234,密码也是1234

TypeError: The view function did not return a valid response. The function either returned None 的解决_第1张图片

点击登录之后, 报如下错误。

TypeError

TypeError: The view function did not return a valid response. The function either returned None or ended without a return statement.

页面截图如下:

TypeError: The view function did not return a valid response. The function either returned None 的解决_第2张图片查网上的 报错,解决办法是路由没有返回东西,于是我改了return语句,if和else都有返回值。

 try:
        # 执行sql语句
        cursor.execute(sql)
        results = cursor.fetchall()
        print(len(results))
        if len(results) == 1:
            #return '登录成功'
            return render_template('pingtable2.html')
        else:
            #return '用户名或密码不正确'
            return render_template('pingtable2.html')
        # 提交到数据库执行
        db.commit()

 但是再次运行的时候还是报同样的错误。

于是我看了以下python控制台。

Traceback (most recent call last):
  File "D:\技术学习\卫生健康委员会\登录页面\cpe项目代码\登录界面\app.py", line 65, in getLoginRequest
    cursor.execute(sql)

  File "D:\python\2\lib\site-packages\pymysql\cursors.py", line 163, in execute
    result = self._query(query)
  File "D:\python\2\lib\site-packages\pymysql\cursors.py", line 321, in _query
    conn.query(q)
  File "D:\python\2\lib\site-packages\pymysql\connections.py", line 505, in query
    self._affected_rows = self._read_query_result(unbuffered=unbuffered)
  File "D:\python\2\lib\site-packages\pymysql\connections.py", line 724, in _read_query_result
    result.read()
  File "D:\python\2\lib\site-packages\pymysql\connections.py", line 1069, in read
    first_packet = self.connection._read_packet()
  File "D:\python\2\lib\site-packages\pymysql\connections.py", line 676, in _read_packet
    packet.raise_for_error()
  File "D:\python\2\lib\site-packages\pymysql\protocol.py", line 223, in raise_for_error
    err.raise_mysql_exception(self._data)
  File "D:\python\2\lib\site-packages\pymysql\err.py", line 107, in raise_mysql_exception
    raise errorclass(errno, errval)
pymysql.err.ProgrammingError: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1")
127.0.0.1 - - [18/Apr/2022 16:53:14] "GET /login?user=1234&password=1234 HTTP/1.1" 500 -
Traceback (most recent call last):
  File "D:\python\2\lib\site-packages\flask\app.py", line 2464, in __call__
    return self.wsgi_app(environ, start_response)
  File "D:\python\2\lib\site-packages\flask\app.py", line 2450, in wsgi_app
    response = self.handle_exception(e)
  File "D:\python\2\lib\site-packages\flask\app.py", line 1867, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "D:\python\2\lib\site-packages\flask\_compat.py", line 39, in reraise
    raise value
  File "D:\python\2\lib\site-packages\flask\app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "D:\python\2\lib\site-packages\flask\app.py", line 1953, in full_dispatch_request
    return self.finalize_request(rv)
  File "D:\python\2\lib\site-packages\flask\app.py", line 1968, in finalize_request
    response = self.make_response(rv)
  File "D:\python\2\lib\site-packages\flask\app.py", line 2098, in make_response
    "The view function did not return a valid response. The"
TypeError: The view function did not return a valid response. The function either returned None or ended without a return statement.
127.0.0.1 - - [18/Apr/2022 16:53:14] "GET /login?__debugger__=yes&cmd=resource&f=style.css HTTP/1.1" 200 -
127.0.0.1 - - [18/Apr/2022 16:53:14] "GET /login?__debugger__=yes&cmd=resource&f=jquery.js HTTP/1.1" 200 -
127.0.0.1 - - [18/Apr/2022 16:53:14] "GET /login?__debugger__=yes&cmd=resource&f=debugger.js HTTP/1.1" 200 -
127.0.0.1 - - [18/Apr/2022 16:53:14] "GET /login?__debugger__=yes&cmd=resource&f=ubuntu.ttf HTTP/1.1" 200 -
127.0.0.1 - - [18/Apr/2022 16:53:14] "GET /login?__debugger__=yes&cmd=resource&f=console.png HTTP/1.1" 200 -

 注意到这个标红的地方,sql语句,我判断,可能是sql语句写错了,没办法往下执行。

db = pymysql.connect(host="localhost", user="root", password="1234", database="testdb")
# 使用cursor()方法获取操作游标
cursor = db.cursor()
# SQL 查询语句
sql = "select * from user where user=" + request.args.get('user') + " and password=" + request.args.get('password')+")"

我注意到sql语句后面有个多的括号,把他删除

再次运行:

TypeError: The view function did not return a valid response. The function either returned None 的解决_第3张图片

成功跳到下一个页面了。

 调错完毕。

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