Introduction

This section describes the basics of Flask's database-related settings. The database shall use SQLite.

Schema settings

The table definition is as follows.

`schema.sql`


DROP TABLE IF EXISTS user;

CREATE TABLE user (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    username TEXT UNIQUE NOT NULL,
    password TEXT NOT NULL
);

Functions for database

The database related functions are as follows.

`db.py`


import sqlite3

import click
from flask import current_app, g
from flask.cli import with_appcontext


def get_db():
    if 'db' not in g:
        g.db = sqlite3.connect(
            current_app.config['DATABASE'],
            detect_types=sqlite3.PARSE_DECLTYPES
        )
        g.db.row_factory = sqlite3.Row

    return g.db


def close_db(e=None):
    db = g.pop('db', None)

    if db is not None:
        db.close()


def init_db():
    db = get_db()

    with current_app.open_resource('schema.sql') as f:
        db.executescript(f.read().decode('utf8'))


@click.command('init-db')
@with_appcontext
def init_db_command():
    """Clear the existing data and create new tables. """
    init_db()
    click.echo('Initialized the database.')


def init_app(app):
    app.teardown_appcontext(close_db)
    app.cli.add_command(init_db_command)

Summary

Here, we explained the basics of database settings. Next time, I'll cover application settings.

Flask database settings