Flask SQLAlchemy-2013断开连接 [英] Flask SQLAlchemy - 2013 Lost Connection

问题描述

因此，我正在尝试使用数据库和Flask动态构建站点.该网站目前可以按照我希望的方式运行，但是仅在大约一分钟之前，我收到一条错误消息，提示:

So I'm attempting a build a site dynamically using a database and flask. The site works how I want it to as of right now, but only for about a minute before I get an error message saying:

sqlalchemy.exc.OperationalError: (pymysql.err.OperationalError) (2013, 'Lost connection to MySQL server during query')

数据库包含我要为每个页面抓取的4个条目，以及一个主页，在其中我仅从数据库的每个条目抓取2个条目. 沿线的某个地方遇到了错误，无法再访问数据库，因此不允许加载使用该数据库的任何页面.

The database contains 4 entries I want to grab for each page, and one main page where I only grab 2 entries from each entry in the database. Somewhere along the line it run into an error where it can no longer access the database and therefore does not allow any more pages that use the database to load.

有人可以帮我弄清楚为什么会这样吗?我对flask和sqlalchemy很陌生

Can anyone help me figure out why this might be happening? I'm very new to flask and sqlalchemy

下面是我的代码:

from flask import Flask
from flask import render_template
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql+pymysql://databaseaddress'
db = SQLAlchemy(app)


class Kitchen(db.Model):
    __tablename__ = 'kitchens'
    id = db.Column('id', db.Integer, primary_key=True)
    description = db.Column('description')
    galleryId = db.Column('galleryId')
    cpo = db.Column('cpo')

    def __init__(self, description, galleryId, cpo):
        self.description = description
        self.galleryId = galleryId
        self.cpo = cpo

    def __repr__(self):
        return '<Gallery %r>' % self.description

    def get_description(self):
        return self.description

    def get_galleryId(self):
        return self.galleryId

    def get_cpo(self):
        return self.cpo

app.py

from flask import Flask
from flask import render_template
from Database import Kitchen

app = Flask(__name__)


@app.route('/')
@app.route('/index')
def main():
    return render_template('index.html')


@app.route('/kitchens', methods=['GET'], defaults={'n': 0})
@app.route('/kitchens/<n>', methods=['GET'])
def kitchens(n):
    row = Kitchen.query.count()
    if int(n) is 0:
        description = []
        for num in range(1, row+1):
            data = Kitchen.query.filter_by(id=num).first()
            description.append(Kitchen.get_description(data))
        return render_template('Gallery Directory.html', portfolio='Kitchens', row=row, description=description)
    elif int(n) >= 1:
        data = Kitchen.query.filter_by(id=n).first()
        description = Kitchen.get_description(data)
        galleryId = Kitchen.get_galleryId(data)
        cpo = Kitchen.get_cpo(data)
        return render_template('Gallery Basic.html', portfolio='Kitchens', description=description, id=int(n),
                               galleryId=galleryId, cpo=cpo, row=row)


if __name__ == "__main__":
    app.run()

错误消息

[2017-02-10 10:17:31,776] ERROR in app: Exception on /kitchens/ 1 [GET]
Traceback (most recent call last):
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/engine/base.py", line 1182, in _execute_context
context)
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/engine/default.py", line 470, in do_execute
cursor.execute(statement, parameters)
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/cursors.py", line 166, in execute
result = self._query(query)
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/cursors.py", line 322, in _query
conn.query(q)
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/connections.py", line 835, in query
self._affected_rows = self._read_query_result(unbuffered=unbuffered)
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/connections.py", line 1019, in _read_query_result
result.read()
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/connections.py", line 1302, in read
first_packet = self.connection._read_packet()
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/connections.py", line 961, in _read_packet
packet_header = self._read_bytes(4)
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/connections.py", line 998, in _read_bytes
2013, "Lost connection to MySQL server during query")
pymysql.err.OperationalError: (2013, 'Lost connection to MySQL server during query')

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/home/devin-matte/.local/lib/python3.5/site-packages/flask/app.py", line 1988, in wsgi_app
response = self.full_dispatch_request()
File "/home/devin-matte/.local/lib/python3.5/site-packages/flask/app.py", line 1641, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/home/devin-matte/.local/lib/python3.5/site-packages/flask/app.py", line 1544, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/home/devin-matte/.local/lib/python3.5/site-packages/flask/_compat.py", line 33, in reraise
raise value
File "/home/devin-matte/.local/lib/python3.5/site-packages/flask/app.py", line 1639, in full_dispatch_request
rv = self.dispatch_request()
File "/home/devin-matte/.local/lib/python3.5/site-packages/flask/app.py", line 1625, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/home/devin-matte/Documents/Coralite/Coralite.py", line 18, in kitchens
row = Kitchen.query.count()
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/orm/query.py", line 3024, in count
return self.from_self(col).scalar()
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/orm/query.py", line 2778, in scalar
ret = self.one()
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/orm/query.py", line 2749, in one
ret = self.one_or_none()
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/orm/query.py", line 2719, in one_or_none
ret = list(self)
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/orm/query.py", line 2790, in __iter__
return self._execute_and_instances(context)
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/orm/query.py", line 2813, in _execute_and_instances
result = conn.execute(querycontext.statement, self._params)
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/engine/base.py", line 945, in execute
return meth(self, multiparams, params)
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/sql/elements.py", line 263, in _execute_on_connection
return connection._execute_clauseelement(self, multiparams, params)
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/engine/base.py", line 1053, in _execute_clauseelement
compiled_sql, distilled_params
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/engine/base.py", line 1189, in _execute_context
context)
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/engine/base.py", line 1393, in _handle_dbapi_exception
exc_info
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/util/compat.py", line 203, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb, cause=cause)
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/util/compat.py", line 186, in reraise
raise value.with_traceback(tb)
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/engine/base.py", line 1182, in _execute_context
context)
File "/usr/local/lib/python3.5/dist-packages/sqlalchemy/engine/default.py", line 470, in do_execute
cursor.execute(statement, parameters)
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/cursors.py", line 166, in execute
result = self._query(query)
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/cursors.py", line 322, in _query
conn.query(q)
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/connections.py", line 835, in query
self._affected_rows = self._read_query_result(unbuffered=unbuffered)
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/connections.py", line 1019, in _read_query_result
result.read()
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/connections.py", line 1302, in read
first_packet = self.connection._read_packet()
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/connections.py", line 961, in _read_packet
packet_header = self._read_bytes(4)
File "/home/devin-matte/.local/lib/python3.5/site-packages/pymysql/connections.py", line 998, in _read_bytes
2013, "Lost connection to MySQL server during query")
sqlalchemy.exc.OperationalError: (pymysql.err.OperationalError) (2013, 'Lost connection to MySQL server during query') [SQL: 'SELECT count(*) AS count_1 \nFROM (SELECT kitchens.id AS kitchens_id, kitchens.description AS kitchens_description, kitchens.`galleryId` AS `kitchens_galleryId`, kitchens.cpo AS kitchens_cpo \nFROM kitchens) AS anon_1']
127.0.0.1 - - [10/Feb/2017 10:17:31] "GET /kitchens/%201 HTTP/1.1" 500 -

推荐答案

此问题与sqlalchemy或flask不相关.它实际上是在mysql服务器端.正在使用的服务器正在超时，并且与非localhost的所有连接断开连接.

This issue was not with sqlalchemy or flask. It was actually on the mysql serverside. The server that was being used was timing out and disconnecting from any connections that were not localhost.

切换到本地sqlite数据库对我来说解决了这个问题，直到我能够在允许远程连接的另一台服务器上托管mysql数据库/将站点托管在数据库的localhost上.

Switching to a local sqlite database solved the issue for me until I was able to get a different server to host the mysql database on that allowed remote connections/hosted the site on the database's localhost.

这篇关于Flask SQLAlchemy-2013断开连接的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！