aliexpress-price-tracker/db.py

#!/usr/bin/python
import psycopg2
import csv
import os

def connect_db(db_settings):
    conn = None
    print("Connecting to the PostgreSQL database...")
    try:
        conn = psycopg2.connect(**db_settings)
        print("Connection success")
    except (Exception, psycopg2.DatabaseError) as error:
        print(error)
    return conn

def add_item(db_settings, itemid, skuid, choice, attributes):
    connection = connect_db(db_settings)
    cursor = connection.cursor()

    cursor.execute("""
    INSERT INTO item (itemid, skuid, choice, attributes)
    VALUES (%s, %s, %s, %s)
    """, (itemid, skuid, choice, attributes))
    connection.commit()
    connection.close()

def add_history_entry(db_settings, itemid, skuid, choice, attributes, price, currency, quantity, discount_percentage):
    connection = connect_db(db_settings)
    cursor = connection.cursor()

    cursor.execute("""
    SELECT *
    FROM item
    WHERE itemid = %s
    AND skuid = %s
    """, (itemid, skuid))

    if cursor.rowcount == 0:
        add_item(db_settings, itemid, skuid, choice, attributes)

    cursor.execute("""
    INSERT INTO history (itemid, skuid, price, currency, quantity, discount_percentage, h_timestamp)
    VALUES (%s, %s, %s, %s, %s, %s, (SELECT LOCALTIMESTAMP))
    """, (itemid, skuid, price, currency, quantity, discount_percentage))
    connection.commit()
    connection.close()


def export_csv(db_settings):
    connection = connect_db(db_settings)
    cursor = connection.cursor()

    cursor.execute("""
    SELECT i.itemid, i.skuid, i.choice, i.attributes, h.quantity, h.discount_percentage, h.price, h.currency, h.h_timestamp
    FROM item i, history h
    WHERE i.itemid = h.itemid and i.skuid = h.skuid
    """)
    results = cursor.fetchall()
    with open(os.path.dirname(os.path.realpath(__file__))+"/output.csv", 'w') as csv_file:
        # Create a CSV writer
        writer = csv.writer(csv_file)
        # write the column names
        writer.writerow([col[0] for col in cursor.description])
        # write the query results
        writer.writerows(results)
    cursor.close()
    connection.close()


def initialize(db_settings):
    connection = connect_db(db_settings)
    cursor = connection.cursor()

    cursor.execute("""
    DROP TABLE IF EXISTS history
    """)
    cursor.execute("""
    DROP TABLE IF EXISTS item
    """)
    cursor.execute("""
    CREATE TABLE item
    (
        itemid  bigint,
        skuid   bigint,
        choice  boolean,
        attributes  text[],
        primary key (itemid,skuid)
    )
    """)
    cursor.execute("""
    CREATE TABLE history
    (
        itemid  bigint,
        skuid   bigint,
        quantity  integer,
        discount_percentage numeric(2),
        price   money,
        currency    varchar(4),
        h_timestamp timestamp,
        foreign key (itemid,skuid) references item(itemid,skuid),
        primary key (itemid,skuid,h_timestamp)
    )
    """)

    connection.commit()
    connection.close()
    print("Database initialized")