From 0eb1161d7a60fdb313f443d19ee347659d88d574 Mon Sep 17 00:00:00 2001 From: s3lph Date: Tue, 5 Jun 2018 22:18:10 +0200 Subject: [PATCH] Added lots of documentation to the Database Facade. --- matemat/db/facade.py | 124 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) diff --git a/matemat/db/facade.py b/matemat/db/facade.py index abd1829..43c6f24 100644 --- a/matemat/db/facade.py +++ b/matemat/db/facade.py @@ -11,25 +11,54 @@ from matemat.db import DatabaseWrapper class DatabaseFacade(object): def __init__(self, filename: str): + """ + Create a new database facade. This does not connect to the SQLite3 database yet. To actually open the + connection, use the Context Manager 'with' syntax (PEP 343), e.g.: + + with Database('path/to/database.sqlite3') as db: + db.foo() + + :param filename: The SQLite3 database file to use. + """ self.db: DatabaseWrapper = DatabaseWrapper(filename) def __enter__(self): + # Pass context manager stuff through to the database wrapper self.db.__enter__() return self def __exit__(self, exc_type, exc_val, exc_tb): + # Pass context manager stuff through to the database wrapper self.db.__exit__(exc_type, exc_val, exc_tb) def transaction(self, exclusive: bool = True): + """ + Begin a new SQLite3 transaction (exclusive by default). You should never need to use the returned object (an + APSW cursor). It is provided in case there is a real need for it (e.g. for unit testing). + + This function should be used with the Context Manager 'with' syntax (PEP 343), e.g.: + + with db.transaction(): + db.foo() + db.bar() + + :param exclusive: Whether to begin an exclusive transaction or not, defaults to True (exclusive). + :return: An APSW cursor. + """ return self.db.transaction(exclusive=exclusive) def list_users(self) -> List[User]: + """ + Return a list of users in the database. + :return: A list of users. + """ users: List[User] = [] with self.db.transaction(exclusive=False) as c: for row in c.execute(''' SELECT user_id, username, email, is_admin, is_member FROM users '''): + # Decompose each row and put the values into a User object user_id, username, email, is_admin, is_member = row users.append(User(user_id, username, email, is_admin, is_member)) return users @@ -40,12 +69,25 @@ class DatabaseFacade(object): email: Optional[str] = None, admin: bool = False, member: bool = True) -> User: + """ + Create a new user. + :param username: The name of the new user. + :param password: The user's password. + :param email: The user's email address, defaults to None. + :param admin: Whether the user is an administrator, defaults to False. + :param member: Whether the user is a member, defaults to True. + :return: A User object representing the created user. + :raises ValueError: If a user with the same name already exists. + """ + # Hash the password. pwhash: str = bcrypt.hashpw(password.encode('utf-8'), bcrypt.gensalt(12)) user_id: int = -1 with self.db.transaction() as c: + # Look up whether a user with the same name already exists. c.execute('SELECT user_id FROM users WHERE username = ?', [username]) if c.fetchone() is not None: raise ValueError(f'A user with the name \'{username}\' already exists.') + # Insert the user into the database. c.execute(''' INSERT INTO users (username, email, password, balance, is_admin, is_member, lastchange) VALUES (:username, :email, :pwhash, 0, :admin, :member, STRFTIME('%s', 'now')) @@ -56,11 +98,22 @@ class DatabaseFacade(object): 'admin': admin, 'member': member }) + # Fetch the new user's rowid. c.execute('SELECT last_insert_rowid()') user_id = int(c.fetchone()[0]) return User(user_id, username, email, admin, member) def login(self, username: str, password: Optional[str] = None, touchkey: Optional[str] = None) -> User: + """ + Validate a user's password or touchkey, and return a User object on success. EITHER password OR touchkey must + be provided, the other one must be None. + :param username: The username to login with. + :param password: The user's password. + :param touchkey: The user's touchkey. + :return: A User object. + :raises ValueError: If none or both of password and touchkey are provided. + :raises AuthenticationError: If the user does not exist or the password or touchkey is wrong. + """ if (password is None) == (touchkey is None): raise ValueError('Exactly one of password and touchkey must be provided') with self.db.transaction(exclusive=False) as c: @@ -80,15 +133,27 @@ class DatabaseFacade(object): return User(user_id, username, email, admin, member) def change_password(self, user: User, oldpass: str, newpass: str, verify_password: bool = True): + """ + Change a user's password. Either the old password must be provided (for a password change by the user + him-/herself), or verify_password must be set to False (for a password change by an administrator). + :param user: User object representing the user to change the password for. + :param oldpass: The old password. + :param newpass: The new password. + :param verify_password: Whether to actually verify the old password, defaults to True. + :raises AuthenticationError: If the user does not exist or oldpass is wrong (if verify_password is True). + """ with self.db.transaction() as c: + # Fetch the old password. c.execute(''' SELECT password FROM users WHERE user_id = ? ''', [user.id]) row = c.fetchone() if row is None: raise AuthenticationError('User does not exist in database.') + # Verify the old password, if it should be verified. if verify_password and not bcrypt.checkpw(oldpass.encode('utf-8'), row[0]): raise AuthenticationError('Old password does not match.') + # Hash the new password and write it to the database. pwhash: str = bcrypt.hashpw(newpass.encode('utf-8'), bcrypt.gensalt(12)) c.execute(''' UPDATE users SET password = :pwhash, lastchange = STRFTIME('%s', 'now') WHERE user_id = :user_id @@ -98,15 +163,27 @@ class DatabaseFacade(object): }) def change_touchkey(self, user: User, password: str, touchkey: Optional[str], verify_password: bool = True): + """ + Change a user's touchkey. Either the old password must be provided (for a password change by the user + him-/herself), or verify_password must be set to False (for a password change by an administrator). + :param user: User object representing the user to change the password for. + :param password: The user's password. + :param touchkey: The new touchkey. + :param verify_password: Whether to actually verify the password, defaults to True. + :raises AuthenticationError: If the user does not exist or password is wrong (if verify_password is True). + """ with self.db.transaction() as c: + # Fetch the password. c.execute(''' SELECT password FROM users WHERE user_id = ? ''', [user.id]) row = c.fetchone() if row is None: raise AuthenticationError('User does not exist in database.') + # Verify the password, if it should be verified. if verify_password and not bcrypt.checkpw(password.encode('utf-8'), row[0]): raise AuthenticationError('Password does not match.') + # Hash the new touchkey and write it to the database. tkhash: str = bcrypt.hashpw(touchkey.encode('utf-8'), bcrypt.gensalt(12)) if touchkey is not None else None c.execute(''' UPDATE users SET touchkey = :tkhash, lastchange = STRFTIME('%s', 'now') WHERE user_id = :user_id @@ -116,6 +193,11 @@ class DatabaseFacade(object): }) def change_user(self, user: User): + """ + Write changes in the User object to the database. + :param user: The user object to update in the database. + :raises DatabaseConsistencyError: If the user represented by the object does not exist. + """ with self.db.transaction() as c: c.execute(''' UPDATE users SET @@ -136,6 +218,11 @@ class DatabaseFacade(object): f'change_user should affect 1 users row, but affected {affected}') def delete_user(self, user: User): + """ + Delete the user represented by the User object. + :param user: The user to delete. + :raises DatabaseConsistencyError: If the user represented by the object does not exist. + """ with self.db.transaction() as c: c.execute(''' DELETE FROM users @@ -147,6 +234,10 @@ class DatabaseFacade(object): f'delete_user should affect 1 users row, but affected {affected}') def list_products(self) -> List[Product]: + """ + Return a list of products in the database. + :return: A list of products. + """ products: List[Product] = [] with self.db.transaction(exclusive=False) as c: for row in c.execute(''' @@ -158,6 +249,14 @@ class DatabaseFacade(object): return products def create_product(self, name: str, price_member: int, price_non_member: int) -> Product: + """ + Creates a new product. + :param name: Name of the product. + :param price_member: Price of the product for members. + :param price_non_member: Price of the product for non-members. + :return: A Product object representing the created product. + :raises ValueError: If a product with the same name already exists. + """ product_id: int = -1 with self.db.transaction() as c: c.execute('SELECT product_id FROM products WHERE name = ?', [name]) @@ -196,6 +295,11 @@ class DatabaseFacade(object): f'change_product should affect 1 products row, but affected {affected}') def delete_product(self, product: Product): + """ + Write changes in the Product object to the database. + :param product: The product object to update in the database. + :raises DatabaseConsistencyError: If the product represented by the object does not exist. + """ with self.db.transaction() as c: c.execute(''' DELETE FROM products @@ -207,6 +311,14 @@ class DatabaseFacade(object): f'delete_product should affect 1 products row, but affected {affected}') def increment_consumption(self, user: User, product: Product, count: int = 1): + """ + Decrement the user's balance by the price of the product, decrement the products stock, and create an entry in + the statistics table. + :param user: The user buying a product. + :param product: The product the user is buying. + :param count: How many instances of the product the user is buying, defaults to 1. + :raises DatabaseConsistencyError: If the user or the product does not exist in the database. + """ with self.db.transaction() as c: c.execute(''' SELECT count @@ -266,6 +378,12 @@ class DatabaseFacade(object): f'increment_consumption should affect 1 products row, but affected {affected}') def restock(self, product: Product, count: int): + """ + Update the stock of a product. + :param product: The product to restock. + :param count: Number of instances of the product to add. + :raises DatabaseConsistencyError: If the product represented by the object does not exist. + """ with self.db.transaction() as c: c.execute(''' UPDATE products @@ -280,6 +398,12 @@ class DatabaseFacade(object): raise DatabaseConsistencyError(f'restock should affect 1 products row, but affected {affected}') def deposit(self, user: User, amount: int): + """ + Update the account balance of a user. + :param user: The user to update the account balance for. + :param amount: The amount to add to the account balance. + :raises DatabaseConsistencyError: If the user represented by the object does not exist. + """ if amount < 0: raise ValueError('Cannot deposit a negative value') with self.db.transaction() as c: