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python - 在数据库中进行一些更改时，Flask Server 需要重新启动吗？

问题描述

我正在使用 Flask 创建 Web 服务。当我对 DB 进行一些更改时，我需要重新启动 Flask 服务器。

db = pymysql.connect("localhost","root","","posdata")
db1 = pymysql.connect("localhost","root","","posdata")

另外我必须创建两个数据库连接才能使某些功能正常工作。如果我只使用一个连接（如上所说的数据库），我会得到

`InterfaceError (0, '')`

所以为了处理 InterfaceError 我创建了两个 db 连接。但现在的问题是，当我对 DB 进行一些更改时，db 工作正常但 db1 不工作，我需要重新启动烧瓶服务器以使 db1 连接工作。

@app.route('/data_url/<customer_name>')
def data(customer_name):
    cursor = db.cursor()
    cursor.execute(" select country_name from countries as c, customers as cu where c.c_id = cu.c_id and cu.customer_id = '%s' " % customer_name)
    data =  cursor.fetchall()
    data = [x[0] for x in data]
    return jsonify(data)


**# query to select TYPE attribute from DB and send it to ajax**

@app.route('/url_for/<customer_name>')
def dt(customer_name):
    cursor = db1.cursor()
    cursor.execute(" select type from customers where customer_id = '%s' " % customer_name)
    data =  cursor.fetchall()
    data = [x[0] for x in data]
    return jsonify(data)

在这里要使@app.route('/url_for/')工作我需要重新启动烧瓶服务器。

使用单个 DB 连接时出现错误回溯

Traceback (most recent call last):
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 2309, in __call__
    return self.wsgi_app(environ, start_response)
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 2295, in wsgi_app
    response = self.handle_exception(e)
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 1741, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\_compat.py", line 35, in reraise
    raise value
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 2292, in wsgi_app
    response = self.full_dispatch_request()
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 1815, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 1718, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\_compat.py", line 35, in reraise
    raise value
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 1813, in full_dispatch_request
    rv = self.dispatch_request()
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\flask\app.py", line 1799, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "C:\Users\OneDrive -\Desktop\Project\TestApp\app.py", line 34, in Request
    cursor.execute('select customer_id from customers')
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\pymysql\cursors.py", line 170, in execute
    result = self._query(query)
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\pymysql\cursors.py", line 328, in _query
    conn.query(q)
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\pymysql\connections.py", line 516, in query
    self._execute_command(COMMAND.COM_QUERY, sql)
  File "C:\Users\AppData\Local\Programs\Python\Python36\lib\site-packages\pymysql\connections.py", line 750, in _execute_command
    raise err.InterfaceError("(0, '')")
pymysql.err.InterfaceError: (0, '')

标签： pythonflask

解决方案

您已经更改了以前的代码，但它并没有反映到您当前正在运行的Flask Server。所以答案是yes，为了反映您对服务器的新修改，您需要重新启动 Flask Server

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