Refactor Win in data_utils.py and Why Flake8 Flags "from queries import *"

[AAdewunmi]

Hi all,

I just did a small refactor in data_utils.py based on DRY, and it cleaned things up nicely.

I noticed repeated code in multiple functions:

with DBcm.UseDatabase(db_details) as db:
results = db.fetchall()

So I extracted that into a helper:

def _fetch_all(sql, params=()):
    """Execute a query and return all rows as a tuple-list."""
    with DBcm.UseDatabase(db_details) as db:
        db.execute(sql, params)
        return db.fetchall()

Each function just calls _fetch_all(...), which reduces repetition and makes intent clearer.

Flake8 issue: from queries import *

Flake8 flagged wildcard imports with:

• F403: from queries import * used; unable to detect undefined names.
• F405: names may be undefined or coming from star imports.

Why this happened:

1. imports hide where names come from.
2. Static analysis tools can’t reliably resolve symbols.

Fix:
Used explicit imports, e.g.

from queries import (
    SQL_CHART_DATA_BY_SWIMMER_EVENT_SESSION,
    SQL_SESSIONS,
    SQL_SWIMMERS_BY_SESSION,
)

I refactored the module to remove repeated DB code and kept each function focused on its query. I also replaced from queries import * with explicit imports to clarify dependencies and avoid Flake8 F403/F405 warnings.

Refactored data_utils.py

from queries import (
    SQL_CHART_DATA_BY_SWIMMER_EVENT_SESSION,
    SQL_SESSIONS,
    SQL_SWIMMERS_EVENTS_BY_SESSION,
    SQL_SWIMMERS_BY_SESSION,
)

import DBcm
db_details = "CoachDB.sqlite3"


def _fetch_all(sql, params=()):
    """Execute a query and return all rows as a tuple-list."""
    with DBcm.UseDatabase(db_details) as db:
        db.execute(sql, params)
        return db.fetchall()


def get_swim_sessions():
    """Return a tuple-list of unique session timestamps."""
    return _fetch_all(SQL_SESSIONS)


def get_session_swimmers(date):
    """When given a date (YYYY-MM-DD), return a tuple-list of swimmers
    and their associated age (filtered by date)."""
    return _fetch_all(SQL_SWIMMERS_BY_SESSION, (date,))


def get_swimmers_events(name, age, date):
    """When given a date (YYYY-DD-MM), swimmer's name, and swimmer's
    age, return
    a tuple-list of events the swimmer swam on that date.
    """
    return _fetch_all(
        SQL_SWIMMERS_EVENTS_BY_SESSION,
        (name, age, date),
    )


def get_swimmers_times(name, age, distance, stroke, date):
    """When given a date (YYYY-MM-DD), swimmer's name, swimmer's age, distance,
    and stroke, return a tuple-list of times the swimmer swam on that date over
    the identified distance/stroke combination.
    """
    return _fetch_all(
        SQL_CHART_DATA_BY_SWIMMER_EVENT_SESSION,
        (name, age, distance, stroke, date),
    )

Hope it helps anyone else working through the same chapter.

Adrian

[headfirstpython]

I can't argue with any of that - thanks! Nice refactoring here.

[AAdewunmi]

Hi Paul,

My pleasure and I enjoyed working through the "Head First Python" book.

Best wishes for the future.

Adrian

[headfirstpython]

The fact that you enjoyed working through my book and engaged so thoughtfully with the material is music to my ears. Best wishes for your future Python travels. 😎

--Paul.