db.py

import sqlite3
from http import HTTPStatus
import flask
from flask import current_app, g, cli
import click

def make_dicts(cursor, row):
    return dict((cursor.description[idx][0], value)
                for idx, value in enumerate(row))

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 = make_dicts

    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')
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)

class SQLiteCurr:
    def __init__(self, app):
        self.app = app
        self.connection = get_db()
        self.cursor = None

    def __enter__(self):
        self.cursor = self.connection.cursor()
        return self.cursor

    def __exit__(self, exc_type, exc_val, exc_tb):
        if exc_tb is None:
            self.connection.commit()
        else:
            self.connection.rollback()
            self.cursor.close()

            self.app.logger.exception(exc_val, exc_info=(exc_type, exc_val, exc_tb), stack_info=True)
            flask.abort(HTTPStatus.INTERNAL_SERVER_ERROR)

        self.cursor.close()