[PYTHON] Connection between flask and sqlite3

-Creating a simple app with flask -Try to create a Home screen -Try to create an authentication function --Try using the database ← ★ Currently here -Try to create CRUD function

Access database

Database installation / configuration

This time we will use SQLite.

• Mac users are installed by default.

• For windows, please install from here. Also, refer to here for the settings.

• Installation confirmation

$ sqlite3 -version
3.28.0 ...

Also, install the ORM (Object Relational Mapper) used this time.

• Install SQLAlchemy

 mac
$ pip3 install Flask-SQLAlchemy

 windows
$ pip install Flask-SQLAlchemy

• Initial setting

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config["SECRET_KEY"] = b'_5#y2L"F4Q8z\n\xec]dasfe/'
app.config["SQLALCHEMY_DATABASE_URI"] = 'sqlite:///flask_blog.db'
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = True

db = SQLAlchemy(app)

import src.views

Model definition

Since we are creating a blog this time, we will have a title and body, and we will also manage the posting date and time in the database. Create a new "models" in the src directory and create "entires.py".

from src import db
from datetime import datetime


class Entry(db.Model):
    __tablename__ = 'entries'
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(50), unique=True)
    text = db.Column(db.Text)
    create_at = db.Column(db.DateTime)
    
    def __init__(self, title=None, text=None):
        self.title = title
        self.text = text
        self.create_at = datetime.now()

Execution of common processing in script

Finally, the contents defined in the model are reflected in the database. There are two reactions to the database:

• Run on console
• Run in script

This time, I will introduce the execution with a script. (This is less likely to make mistakes and is often used in actual development environments.)

First, install the libraries needed to run the script.

 mac
$ pip3 install Flask-Script

 windows
$ pip install Flask-Script

The actual script is as follows.

import sys
sys.dont_write_bytecode = True

from flask_script import Command
from flask_script import Manager

from src import app
from src import db

class InitDB(Command):
    def run(self):
        db.create_all()

if __name__ == '__main__':
    m = Manager(app)
    m.add_command('init_db', InitDB())
    m.run()
    

Execute the created script file.

 mac 
$ python3 manage.py init_db

 windows
$ python manage.py init_db

After running, you should see a file called'flask_blog.db'created in the'src' directory.