Python: Pymysql hangs silently with no response?

Question

The first application using Python.

My application hangs on pymysql calls, is this library stable?

Just trying to connect to a MySQL database here, but every Python package seems to be difficult to use? In any other language it's very simple and has no weird problems.

migrateFresh.py：

import pymysql.cursors
import os
import glob
from bootstrap import *

reset_database()
migrate_and_seed()

Then I have bootstrap.py:

import pymysql.cursors
from dotenv import load_dotenv
import os
import glob

load_dotenv()

def get_connection (database = ''):
    return pymysql.connect(
        host = os.environ.get("DB_HOST"),
        user = os.environ.get("DB_USER"),
        password = os.environ.get("DB_PASS"),
        database = database,
        cursorclass=pymysql.cursors.DictCursor)

def reset_database():
    connection = get_connection()

    with connection:
        with connection.cursor() as cursor:
            cursor.execute(f'DROP DATABASE IF EXISTS {os.environ.get("DB_NAME")};')
            cursor.execute(f'CREATE DATABASE {os.environ.get("DB_NAME")};')

        connection.commit()

    print('Database has been reset')

def migrate_and_seed():
    connection = get_connection(os.environ.get("DB_NAME"))

    with connection:
        with connection.cursor() as cursor:
            for f in sorted(glob.glob("migrations/*.sql")):
                print(f)
                with open(f, "r") as infile:
                    query = infile.read()
                    cursor.execute(query)

        connection.commit()

        with connection.cursor() as cursor:
            for f in sorted(glob.glob("seeders/*.sql")):
                print(f)
                with open(f, "r") as infile:
                    query = infile.read()
                    cursor.execute(query)

        connection.commit()

Answer 1

I recommend that you split the migration and seed functions and enter the connection context manager separately in each function:

import pymysql.cursors
from dotenv import load_dotenv
import os
import glob

load_dotenv()


def get_connection(database=''):
    return pymysql.connect(
        host=os.environ.get("DB_HOST"),
        user=os.environ.get("DB_USER"),
        password=os.environ.get("DB_PASS"),
        database=database,
        cursorclass=pymysql.cursors.DictCursor)


def reset_database():
    connection = get_connection()

    with connection:
        with connection.cursor() as cursor:
            cursor.execute(f'DROP DATABASE IF EXISTS {os.environ.get("DB_NAME")};')
            cursor.execute(f'CREATE DATABASE {os.environ.get("DB_NAME")};')

        connection.commit()

    print('Database has been reset')


def migrate_and_seed():
    ok = migrate()
    if not ok:
        print("migration failed. not seeding...")
        return
    ok = seed()
    if not ok:
        print("seeding failed.")


def migrate():
    try:
        with get_connection(os.environ.get("DB_NAME")) as connection:
            with connection.cursor() as cursor:
                for f in sorted(glob.glob("migrations/*.sql")):
                    print(f)
                    with open(f, "r") as infile:
                        query = infile.read()
                        cursor.execute(query)
    
            connection.commit()
        return True
    except Exception as e:
        print("Migrate Exception:", e)
        return False
    
    
def seed():
    try:
        with get_connection(os.environ.get("DB_NAME")) as connection:
            with connection.cursor() as cursor:
                for f in sorted(glob.glob("seeders/*.sql")):
                    print(f)
                    with open(f, "r") as infile:
                        query = infile.read()
                        cursor.execute(query)
        
            connection.commit()
    except Exception as e:
        print("Seed Exception:", e)
        return False