Python mysql (using pymysql) auto reconnect

Question

I\'m not sure if this is possible, but I\'m looking for a way to reconnect to mysql database when the connection is lost. All the connections are held in a gevent queue but that

Answer 1

The easiest way is to check the connection right before sending a query.

You can do this by creating a small class that contains two methods: connect and query:

import pymysql
import pymysql.cursors

class DB:
    def connect(self):
        self.conn = pymysql.connect(
                             host=hostname,
                             user=username,
                             password=password,
                             db=dbname,
                             charset='utf8mb4',
                             cursorclass=pymysql.cursors.DictCursor,
                             port=3306)

    def query(self, sql):
        try:
            cursor = self.conn.cursor()
            cursor.execute(sql)
        except pymysql.OperationalError:
            self.connect()
            cursor = self.conn.cursor()
            cursor.execute(sql)
        return cursor

db = DB()

Now, whenever you send a query using db.query("example SQL") the request is automatically prepared to encounter a connection error and reconnects using self.connect() if it needs to.

Remember: This is a simplified example. Normally, you would want to let PyMySQL help you escape special characters in your queries. To do that, you would have to add a 2nd parameter in the query method and go from there.