Add db config

import json

from pathlib import Path

from typing import Optional

def get_database_uri(instance_path: Path) -> str:

    """

    Get the URI to the application database for use with SQLAlchemy.

    1. If ./instance/db.conf.json contains a "SQLALCHEMY_DATABASE_URI" key, this URI is returned.

    2. Otherwise, a URI pointing to the SQLite database ./instance/clams.db is returned.

    """

    return load_uri_from_config(instance_path / "db.conf.json") or get_uri_for_sqlite(

        instance_path / "clams.db"

    )

def get_uri_for_sqlite(db_path: Path) -> str:

    return f"sqlite+pysqlite:///{db_path.absolute().resolve()}"

def load_uri_from_config(db_conf_json: Path) -> Optional[str]:

    try:

        with open(db_conf_json) as f:

            db_conf = json.load(f)

            return db_conf["SQLALCHEMY_DATABASE_URI"]

    except (FileNotFoundError, KeyError):

        return None