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Merge branch 'db-doc' into 'master'

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Documentation for the MatematDatabase Facade

See merge request s3lph/matemat!4
This commit is contained in:
s3lph 2018-06-07 12:58:03 +00:00
commit 2a53952003
4 changed files with 150 additions and 5 deletions
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1
.gitignore vendored
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@ -5,6 +5,7 @@
*.pyc
**/*.egg-info/
*.coverage
**/.mypy_cache/
*.sqlite3
*.db

2
matemat/db/__init__.py
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@ -1,3 +1,3 @@
from .wrapper import DatabaseWrapper
from .facade import DatabaseFacade as Database
from .facade import MatematDatabase

148
matemat/db/facade.py
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@ -8,28 +8,69 @@ from matemat.exceptions import AuthenticationError, DatabaseConsistencyError
from matemat.db import DatabaseWrapper
class DatabaseFacade(object):
class MatematDatabase(object):
"""
This class provides a facade that abstracts every (TM) needed database access in high level functions.
Usage example (creating a user, changing the users touchkey, login as that user and delete the user:
with MatematDatabase('/srv/matemat/production.sqlite3') as db:
user: User = db.create_user('testuser', 'supersecurepassword')
db.change_touchkey(user, 'supersecurepassword', '048cdef')
user2: User = db.login('testuser', touchkey='048cdef')
db.delete_user(user2)
"""
def __init__(self, filename: str) -> None:
"""
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 MatematDatabase('path/to/database.sqlite3') as db:
db.foo()
:param filename: The SQLite3 database file to use.
"""
self.db: DatabaseWrapper = DatabaseWrapper(filename)
def __enter__(self) -> 'DatabaseFacade':
def __enter__(self) -> 'MatematDatabase':
# Pass context manager stuff through to the database wrapper
self.db.__enter__()
return self
def __exit__(self, exc_type: Type, exc_val: Any, exc_tb: Any) -> None:
# Pass context manager stuff through to the database wrapper
self.db.__exit__(exc_type, exc_val, exc_tb)
def transaction(self, exclusive: bool = True) -> Any:
"""
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 +81,25 @@ 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 +110,22 @@ 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 +145,27 @@ 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) -> None:
"""
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 +175,27 @@ class DatabaseFacade(object):
})
def change_touchkey(self, user: User, password: str, touchkey: Optional[str], verify_password: bool = True) -> None:
"""
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 +205,11 @@ class DatabaseFacade(object):
})
def change_user(self, user: User) -> None:
"""
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 +230,11 @@ class DatabaseFacade(object):
f'change_user should affect 1 users row, but affected {affected}')
def delete_user(self, user: User) -> None:
"""
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 +246,10 @@ 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 +261,14 @@ 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 +307,11 @@ class DatabaseFacade(object):
f'change_product should affect 1 products row, but affected {affected}')
def delete_product(self, product: Product) -> None:
"""
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
@ -207,7 +323,16 @@ 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) -> None:
"""
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 units 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:
# Retrieve the consumption entry for the (user, product) pair, if any.
c.execute('''
SELECT count
FROM consumption
@ -219,6 +344,7 @@ class DatabaseFacade(object):
})
row = c.fetchone()
if row is None:
# If the entry does not exist, create a new one.
c.execute('''
INSERT INTO consumption (user_id, product_id, count)
VALUES (:user_id, :product_id, :count)
@ -228,6 +354,7 @@ class DatabaseFacade(object):
'count': count
})
else:
# If the entry exists, update the consumption count.
c.execute('''
UPDATE consumption
SET count = count + :count
@ -237,10 +364,12 @@ class DatabaseFacade(object):
'product_id': product.id,
'count': count
})
# Make sure exactly one consumption row was updated/inserted.
affected = c.execute('SELECT changes()').fetchone()[0]
if affected != 1:
raise DatabaseConsistencyError(
f'increment_consumption should affect 1 consumption row, but affected {affected}')
# Compute the cost of the transaction and subtract it from the user's account balance.
c.execute('''
UPDATE users
SET balance = balance - :cost
@ -248,10 +377,12 @@ class DatabaseFacade(object):
'user_id': user.id,
'cost': count * product.price_member if user.is_member else count * product.price_non_member
})
# Make sure exactly one user row was updated.
affected = c.execute('SELECT changes()').fetchone()[0]
if affected != 1:
raise DatabaseConsistencyError(
f'increment_consumption should affect 1 users row, but affected {affected}')
# Subtract the number of purchased units from the product's stock.
c.execute('''
UPDATE products
SET stock = stock - :count
@ -260,12 +391,19 @@ class DatabaseFacade(object):
'product_id': product.id,
'count': count
})
# Make sure exactly one product row was updated.
affected = c.execute('SELECT changes()').fetchone()[0]
if affected != 1:
raise DatabaseConsistencyError(
f'increment_consumption should affect 1 products row, but affected {affected}')
def restock(self, product: Product, count: int) -> None:
"""
Update the stock of a product.
:param product: The product to restock.
:param count: Number of units 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 +418,12 @@ class DatabaseFacade(object):
raise DatabaseConsistencyError(f'restock should affect 1 products row, but affected {affected}')
def deposit(self, user: User, amount: int) -> None:
"""
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:

4
matemat/db/test/test_facade.py
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@ -3,14 +3,14 @@ import unittest
import bcrypt
from matemat.db import Database
from matemat.db import MatematDatabase
from matemat.exceptions import AuthenticationError, DatabaseConsistencyError
class DatabaseTest(unittest.TestCase):
def setUp(self) -> None:
self.db = Database(':memory:')
self.db = MatematDatabase(':memory:')
def test_create_user(self) -> None:
with self.db as db: