pg.py

import psycopg2
import os

pg = psycopg2.connect(
    dbname=os.getenv("POSTGRES_DB"),
    user=os.getenv("POSTGRES_USER"),
    password=os.getenv("POSTGRES_PASSWORD"),
    port=os.getenv("POSTGRES_PORT"),
    host=os.getenv("POSTGRES_HOST"),
)


def get_chapters(ids):
    cur = pg.cursor()
    cur.execute(
        """
SELECT
  ch.id,
  ch.explanation
FROM
  chapters ch
WHERE
  ch.id = ANY (%s);
    """,
        (ids,),
    )
    data = cur.fetchall()
    cur.close()

    chapters = list(map(lambda x: {"id": x[0], "explanation": x[1]}, data))

    ordered_chapters = []
    for id in ids:
        chapter = next(
            (ch for ch in chapters if ch["id"] == id),
            None,
        )
        if chapter:
            ordered_chapters.append(chapter)

    return ordered_chapters