hamster-tools/hamstertools/db.py

import sqlite3

class DatabaseManager:
    def __init__(self, database_name):
        self.conn = sqlite3.connect(database_name)
        self.cursor = self.conn.cursor()

    def get_conn(self):
        return self.conn

    def get_cursor(self):
        return self.cursor

    def close(self):
        self.conn.close()

class BaseORM:
    def __init__(self, db_manager, table_name, id, **kwargs):
        self.db_manager = db_manager
        self.conn = db_manager.get_conn()
        self.cursor = db_manager.get_cursor()
        self.id = id
        self.table_name = table_name
        for key, value in kwargs.items():
            setattr(self, key, value)

    def delete(self):
        self.cursor.execute(f"DELETE FROM {self.table_name} WHERE id=?", (self.id,))
        self.conn.commit()


class Category(BaseORM):
    def __init__(self, db_manager, id, name, activity_count):
        super().__init__(db_manager, "categories", id, name=name,
                         activity_count=activity_count)

    @staticmethod
    def list_categories(db_manager, filter_query=None):
        cursor = db_manager.get_cursor()
        where = ""
        if filter_query is not None:
            where = "WHERE categories.name LIKE ?"
        sql = f"""
            SELECT
                categories.id,
                COALESCE(categories.name, ""),
                COUNT(activities.id) AS activity_count
            FROM
                categories
            LEFT JOIN
                activities
            ON
                categories.id = activities.category_id
            {where}
            GROUP BY
                categories.id
            """
        if filter_query is not None:
            cursor.execute(sql, ("%{}%".format(filter_query),))
        else:
            cursor.execute(sql)
        rows = cursor.fetchall()
        return [Category(db_manager, row[0], row[1], row[2]) for row in rows]

    @staticmethod
    def get_by_id(db_manager, category_id):
        cursor = db_manager.get_cursor()
        cursor.execute("""
            SELECT
                categories.id,
                categories.name,
                COUNT(activities.id) AS activity_count
            FROM
                categories
            LEFT JOIN
                activities
            ON
                categories.id = activities.category_id
            WHERE
                categories.id = ?
        """, (category_id,))

        row = cursor.fetchone()
        if row:
            return Category(db_manager, row[0], row[1], row[2])
        return None


class Activity(BaseORM):
    def __init__(self, db_manager, id, name, category_id, category_name, facts_count):
        super().__init__(db_manager, "activities", id, name=name, category_id=category_id)
        self.category_name = category_name
        self.facts_count = facts_count

    @staticmethod
    def list_activities(db_manager, filter_query=None):
        cursor = db_manager.get_cursor()
        where = ""
        if filter_query is not None:
            where = "WHERE categories.name LIKE ? or activities.name like ?"
        sql = f"""
            SELECT
                activities.id,
                activities.name,
                categories.id,
                COALESCE(categories.name, ""),
                COUNT(facts.id) AS facts_count
            FROM
                activities
            LEFT JOIN
                categories
            ON
                activities.category_id = categories.id
            LEFT JOIN
                facts
            ON
                activities.id = facts.activity_id
            {where}
            GROUP BY
                activities.id
        """

        if filter_query is not None:
            cursor.execute(sql, ("%{}%".format(filter_query),) * 2 )
        else:
            cursor.execute(sql)

        rows = cursor.fetchall()
        return [Activity(db_manager, row[0], row[1], row[2], row[3], row[4]) for row in rows]

    @staticmethod
    def get_by_id(db_manager, activity_id):
        cursor = db_manager.get_cursor()
        cursor.execute("""
            SELECT
                activities.id,
                activities.name,
                categories.id,
                COALESCE(categories.name, ""),
                COUNT(facts.id) AS facts_count
            FROM
                activities
            LEFT JOIN
                categories
            ON
                activities.category_id = categories.id
            LEFT JOIN
                facts
            ON
                activities.id = facts.activity_id
            WHERE
                activities.id = ?
        """, (activity_id,))

        row = cursor.fetchone()
        if row:
            return Activity(db_manager, row[0], row[1], row[2], row[3], row[4])
        return None


class Fact(BaseORM):
    def __init__(self, db_manager, id, activity_id):
        super().__init__(db_manager, "facts", id, activity_id=activity_id)

    @staticmethod
    def list_facts(db_manager):
        cursor = db_manager.get_cursor()
        cursor.execute("SELECT * FROM facts")
        rows = cursor.fetchall()
        return [Fact(db_manager, row[0], row[1]) for row in rows]