Simple Tile server Blueprint for Flask Python framework integration

tile_server.py

import os
import sqlite3

from io import BytesIO

from flask import g
from flask import abort
from flask import Blueprint
from flask import current_app


blueprint = Blueprint(
    name='map_tiles',
    import_name=__name__,
)


@blueprint.before_request
def before_request():
    """
    Ensure database is connected for each request
    """
    g.db = sqlite3.connect("map.mbtiles")


@blueprint.teardown_request
def teardown_request(exception):
    """
    Cleanup database afterwards
    """
    if hasattr(g, 'db'):
        g.db.close()


@blueprint.route("/map-tiles/<int:zoom>/<int:column>/<int:row>.png")
def query_tile(zoom, column, row):
    """
    Get a tile from the MBTiles database
    :param zoom:
    :param column:
    :param row:
    """
    # row = (2 ** zoom) - 1 - row

    cursor = g.db.execute(
        """
            SELECT tile_data FROM tiles 
            WHERE zoom_level = ? AND tile_column = ? AND tile_row = ?;        
        """, (zoom, column, row)
    )

    result = cursor.fetchone()

    if not result:
        abort(404)

    the_image = bytes(result[0])

    return current_app.response_class(
        BytesIO(the_image).read(),
        mimetype='image/png'
    )