I am trying to implement a database in my python 3 program. I am using SQLite 3. I don't really understand how to use my DBHelper class.
In order to use my DBHelper, I would need to instantiate a DBHelper object and call a function (insert, etc.). However, each time I instantiate an object, a new connection is made to my database.
I am confused because it looks like I am connecting to the database multiple times, when I feel like I should only be connecting once at the start of the program. But if I don't instantiate a DBHelper object, I cannot use the functions that I need.
Having multiple connections like this also sometimes locks my database.
What is the correct way to implement SQLite in my program?
Edit: I need to use the same sql db file across multiple other classes
import sqlite3
class DBHelper:
def __init__(self, dbname="db.sqlite"):
self.dbname = dbname
try:
self.conn = sqlite3.connect(dbname)
except sqlite3.Error as e:
log().critical('local database initialisation error: "%s"', e)
def setup(self):
stmt = "CREATE TABLE IF NOT EXISTS users (id integer PRIMARY KEY)"
self.conn.execute(stmt)
self.conn.commit()
def add_item(self, item):
stmt = "INSERT INTO users (id) VALUES (?)"
args = (item,)
try:
self.conn.execute(stmt, args)
self.conn.commit()
except sqlite3.IntegrityError as e:
log().critical('user id ' + str(item) + ' already exists in database')
def delete_item(self, item):
stmt = "DELETE FROM users WHERE id = (?)"
args = (item,)
self.conn.execute(stmt, args)
self.conn.commit()
def get_items(self):
stmt = "SELECT id FROM users"
return [x[0] for x in self.conn.execute(stmt)]
You can use singleton
design pattern in your code. You instantiate your connection once, and each time you call __init__
it will return the same connection. For more information go to here .
Remember, if you are accessing the connection using concurrent workflows, you have to either implement safe access to the database connection inside DBHelper
. Read SQLite documents for more information.
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