weakly-referenced object when connect to mysql in python

description-mysql_weakly-referenced object

I came across this issue using the following code file

the error message is ReferenceError: weakly-referenced object no longer exists

reason is in the mysql/connector/cursor.py file

see these lines:
  def _set_connection(self, connection):
        """Set the connection"""
        try:
            self._connection = weakref.proxy(connection)
            self._connection._protocol  # pylint: disable=W0212,W0104
        except (AttributeError, TypeError):
            raise errors.InterfaceError(errno=2048)

because the connection is weakref, so when we use its reference, it is unsafe.

To avoid this issue, use the test1 method.

mysqlconnector.py

import mysql.connector as connector

def connection():

    config = {
        "user": "root",
        "password": "password",
        "host": "localhost",
        "port": 3306,
        "database": "pydb"
    }
    try:
        c = connector.connect(**config)
        return c
    except:
        print "connection error"
        exit(1)

def test(): # error method
    cur= connection().cursor() 
    cur.execute("select version();")
    print cur.fetchone()

def test1(): #no error method
    cn = connection()
    cur = cn.cursor()
    cur.execute("select version;")
    print cur.fetchone()

works like charm thanx

perfect, it worked !!

it works! thanks!

I also got this error because of the connection going out of scope. connector.connect().cursor() has a reference to connector.connect(). If the latter goes out of scope, the cursor breaks:

def make_cursor:
    conn = mysql.connector.connect(...)
    return conn.cursor() # conn does not exist after this returns

def test3:
    cursor = make_cursor()
    cursor.execute(...) # does not work

The solution was to make a class to ensure conn does not get dropped:

class Conn:
    def __init__(self):
        self.conn = mysql.connector.connect(...)
        self.cursor = self.conn.cursor()

def test4:
    conn = Conn()
    conn.cursor.execute(...) # works

Perfect !!! worked (y)

I also got this error because of the connection going out of scope. connector.connect().cursor() has a reference to connector.connect(). If the latter goes out of scope, the cursor breaks:

def make_cursor:
    conn = mysql.connector.connect(...)
    return conn.cursor() # conn does not exist after this returns

def test3:
    cursor = make_cursor()
    cursor.execute(...) # does not work

The solution was to make a class to ensure conn does not get dropped:

class Conn:
    def __init__(self):
        self.conn = mysql.connector.connect(...)
        self.cursor = self.conn.cursor()

def test4:
    conn = Conn()
    conn.cursor.execute(...) # works

Worked for me.. thanks mate !

perfect.. works spot on!!

please i don't know which code I have to use it
I have this error message can anyone help
weakly-referenced object no longer exists

thanks it work

@shehabhy1 test1 function solved that issue perfectly for me (reference connection and support in separate lines). Though I hope you solved the problem since then :D

Kudos @op for the clear and simple explaination!