sqlite_get_list_from_table.py

"""Useful tools for reading sqlite database tables into Python data structures.
Each row of your database table is converted into a namedtuple with fieldnames
taken from the sqlite table definition.  Using the namedtuple._asdict() method
allows you to use treat each table as a list of dicts or if your table has a
primary key which is unique for each row in the table, as a dict of dicts.

get_list_from_table() + get_dict_from_table() is 12 lines because of the
useful uniqueness test in the dict routine and because doing camelize()
inline would make the code too difficult to understand.
"""

import collections, sqlite3  # noqa

db_filename = "my.db"


def get_list_from_table(sqlite_connection, table_name):
    """convert an sqlite database table into a list of namedtuples."""

    def camelize(s):  # 'aa_bb_cc_dd' --> 'AaBbCcDd'
        return "".join(word.title() for word in s.split("_"))

    cursor = sqlite_connection.execute(f"SELECT * FROM {table_name}")
    col_names = " ".join(col_desc[0] for col_desc in cursor.description)
    nt = collections.namedtuple(camelize(table_name), col_names)
    return [nt(*row) for row in cursor.fetchall()]


def get_dict_from_table(sqlite_connection, table_name, key_col_name="id"):
    """convert an sqlite database table into a dict of namedtuples
    useful for tables where each row has a unique primary key.
    """
    the_list = get_list_from_table(sqlite_connection, table_name)
    the_dict = {row._asdict()[key_col_name]: row for row in the_list}
    assert len(the_dict) == len(the_list), (
        f"In {table_name}, {key_col_name} is not unique: "
        f"{len(the_dict)} {len(the_list)}"
    )
    return the_dict


def get_services():
    with sqlite3.connect(db_filename) as conn:
        return get_dict_from_table(conn, "service")


def get_employee_dict():
    with sqlite3.connect(db_filename) as conn:
        return get_dict_from_table(conn, "employee", "employee_id")


services = get_services()
employee_dict = get_employee_dict()

for data in (services, employee_dict):
    print(
        "\n".join(
            str(row) for row in (data.values() if isinstance(data, dict) else data)
        )
    )
    print("")