For a hobby project I'm doing at the moment I want to write an object oriented python program.But one of the first issue I'm running into is creating a class for my (MySQL) database.
I am trying to use as few packages as possible and I want to try to write the database class by using only pymysql.The problem is that there is an overwhelming amount of libraries and a lack of explanation on writing a good database class in python.
Any suggestions and especially examples would be much appreciated
When having the exact same situation, I found the mysql-connector-python class with which I created a small "model" to call from other classes. This is a cut-down version which shows various db calls. As you can see I have a config class which holds all db authentication info and more).
# dependancy: mysql-connector-python (https://dev.mysql.com/downloads/connector/python/2.1.html)
import mysql.connector
import time
import config
import HTMLParser
import StringIO
html_parser = HTMLParser.HTMLParser()
try:
connection = mysql.connector.connect( user=config.DB_USER, password=config.DB_PASSWORD,
host = config.DB_HOST, database=config.DB_DATABASE, unix_socket=config.UNIX_SOCKET)
cursor = connection.cursor()
except mysql.connector.Error as err:
logger.log('Database connection failed for '+config.DB_USER+'@'+config.DB_HOST+'/'+config.DB_DATABASE)
exit()
def get_bad_words():
sql = ("SELECT word FROM word_blacklist")
results = execute(sql)
return results
def get_moderation_method():
sql = ("SELECT var_value FROM settings "
"WHERE var_key = %(key)s")
results = execute(sql, True, {'key':'moderation_method'})
return results[0]
def current_events():
sql = ("SELECT count(id) FROM events WHERE event_date >= DATE_SUB(NOW(), INTERVAL 2 hour) AND event_date <= DATE_ADD(NOW(), INTERVAL 5 hour)")
results = execute(sql, True)
return results[0]
def insert_social_post(channel, filter_type, post_id, validate, user_name, user_id, user_profile_picture, text, post_date, image_url, state):
try:
san_user_name = html_parser.unescape(user_name.encode('utf-8').strip()).decode("utf8").encode('ascii','ignore')
except:
san_user_name = html_parser.unescape(user_name.strip())
try:
san_text = html_parser.unescape(text.encode('utf-8').strip()).decode("utf8").encode('ascii','ignore')
except:
san_text = html_parser.unescape(text.strip())
insert_post = ("INSERT IGNORE INTO social_posts "
"(channel, filter_type, post_id, validate, user_name, user_id, user_profile_picture, text, post_date, image_url, state)"
"VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)")
execute(insert_post, False, [channel, filter_type, str(post_id), validate,
san_user_name.strip(), user_id, user_profile_picture, san_text.strip(), post_date, image_url, state], True)
def delete_posts(ids):
fmt = ','.join(['%s'] * len(ids))
cursor.execute("DELETE FROM `social_posts` WHERE id IN (%s)" % fmt,
tuple(ids))
connection.commit()
def update_campaigns(campaigns):
sql = ("UPDATE social_campaigns "
"SET last_updated = NOW()"
"WHERE id IN ("+(','.join(str(c) for c in campaigns))+")")
execute(sql, False, None, True)
def execute(tuple, single = False, args = {}, commit = False):
cursor.execute(tuple, args)
if commit == True:
connection.commit()
else:
if single == True:
return cursor.fetchone()
else:
return cursor.fetchall()
def lastrowid():
return cursor.lastrowid
def close():
connection.close()
Call upon the class like this:
import db
bad_words = db.get_bad_words()
import sqlite3
"""singleton class to deal with db"""
'''same can be use for pymysql just replace the sqlite3 with pymysql'''
class DBConnection:
instance = None
def __new__(cls, *args, **kwargs):
if cls.instance is None:
cls.instance = super().__new__(DBConnection)
return cls.instance
return cls.instance
def __init__(self, db_name='you-db-name'):
self.name = db_name
# connect takes url, dbname, user-id, password
self.conn = self.connect(db_name)
self.cursor = self.conn.cursor()
def connect(self):
try:
return sqlite3.connect(self.name)
except sqlite3.Error as e:
pass
def __del__(self):
self.cursor.close()
self.conn.close()
# write your function here for CRUD operations
