Using MySQL in Flask

Question

Can someone share example codes in Flask on how to access a MySQL DB? There have been documents showing how to connect to sqlite but not on MySQL.

Thank you very muc

Answer 1

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://username:password@server/db'
db = SQLAlchemy(app)


class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True)
    email = db.Column(db.String(120), unique=True)

    def __init__(self, username, email):
        self.username = username
        self.email = email

    def __repr__(self):
        return '<User %r>' % self.username

help link

Answer 2

we can use mysql using app.config to set the configurations. in future you should not use only development environment, you will need to automatically set the env while in production env.

we should always go for oops concept

firstly we should make a file where it will check and set mysql config for production/development env and set the values to app.config.

# config.py you can put this file anywhere in the project
class Config(object):
    DEBUG = False
    TESTING = False


class DevelopmentConfig(Config):
    """
    Development configurations
    """
    MYSQL_DATABASE_USER = 'root'
    MYSQL_DATABASE_PASSWORD = ''
    MYSQL_DATABASE_HOST = '127.0.0.1'
    MYSQL_DATABASE_DB = 'FlaskProject'  # can be any

    DEBUG = True


class ProductionConfig(Config):
    """
    Production configurations
    """
    MYSQL_DATABASE_USER = 'yourusername'
    MYSQL_DATABASE_PASSWORD = 'yourpassword'
    MYSQL_DATABASE_HOST = 'linktoyourdb' # eg to amazone db :- yourdbname.xxxxxxxxxx.us-east-2.rds.amazonaws.com
    MYSQL_DATABASE_DB = 'yourdbname'

    DEBUG = False

after that use pip3 install flask-mysql

# app.py
from flask import Flask,
from flaskext.mysql import MySQL

app = Flask(__name__)
mysql = MySQL()
if app.config['ENV'] == 'production':
    app.config.from_object('config.ProductionConfig')
else:
    app.config.from_object('config.DevelopmentConfig')
mysql.init_app(app)

@app.route('/')
def yrfunname():
    try:
        conn = mysql.connect()
        cursor = conn.cursor()
        cursor.execute("SELECT * from yrtablename")
        data = cursor.fetchone()
        conn.commit()
        cursor.close()
        return 'success', 200
    except Exception as fail:
        print("Something is wrong with your database user name or password {}".format(fail))
    

Now flask will auto handle the env. you only need to push yr code to production. As your project become bigger you dont have to make db conn again and again. You can use another py file for db connection and use that db connection anywhere in the project.

I am also new to this but i have done lot of research then got this.