fort 2025.0

The Python database micropackage

fort

The Python database micropackage

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fort is a thin database wrapper for programmers who love to write SQL. Use it when SQLAlchemy is too much.

Usage

Start by initializing an object for your database, providing a connection string:

import fort

db = fort.PostgresDatabase('postgres://user:password@host/database')

Each of fort's database classes provides a small set of methods that makes working with SQL simple. You can immediately begin making queries to the database:

import uuid

db.u('CREATE TABLE widgets (id uuid PRIMARY KEY, name text)')

my_id = uuid.uuid4()
db.u('INSERT INTO widgets (id, name) VALUES (%(id)s, %(name)s)', {'id': my_id, 'name': 'Thingy'})

for row in db.q('SELECT id, name FROM widgets'):
    print(row['id'], row['name'])

my_widget = db.q_one('SELECT id, name FROM widgets WHERE id = %(id)s', {'id': my_id})
print(my_widget['name'])

my_widget_name = db.q_val('SELECT name FROM widgets WHERE id = %(id)s', {'id': my_id})
print(my_id, my_widget_name)

Using one of fort's database classes directly is fine, but it is better to consolidate your SQL statements by subclassing one of fort's classes and adding your own methods:

class MyDatabase(fort.PostgresDatabase):

    def migrate(self):
        self.u('CREATE TABLE widgets (id uuid PRIMARY KEY, name text)')

    def add_widget(self, widget_name: str) -> uuid.UUID:
        new_id = uuid.uuid4()
        sql = 'INSERT INTO widgets (id, name) VALUES (%(id)s, %(name)s)'
        params = {'id': new_id, 'name': widget_name}
        self.u(sql, params)
        return new_id

    def list_widgets(self) -> List[Dict]:
        return self.q('SELECT id, name FROM widgets')

    def get_widget(self, widget_id: uuid.UUID) -> Optional[Dict]:
        sql = 'SELECT id, name FROM widgets WHERE id = %(id)s'
        return self.q_one(sql, {'id': widget_id})

    def get_widget_name(self, widget_id: uuid.UUID) -> Optional[str]:
        sql = 'SELECT name FROM widgets WHERE id = %(id)s'
        return self.q_val(sql, {'id': widget_id})

db = MyDatabase('postgres://user:password@host/database')
db.migrate()

my_id = db.add_widget('Thingy')

for widget in db.list_widgets():
    print(widget['id'], widget['name'])

my_widget = db.get_widget(my_id)
print(my_widget['id'], my_widget['name'])

my_widget_name = db.get_widget_name(my_id)
print(my_id, my_widget_name)

Database class methods

The following methods come with every fort database class:

def u(self, sql: str, params: Dict = None) -> int: ...
    """
    Execute a statement and return the number of rows affected.
    Use this method for CREATE, INSERT, and UPDATE statements.
    """

def q(self, sql: str, params: Dict = None) -> List[Dict]: ...
    """
    Execute a statement and return all results.
    Use this method for SELECT statements.
    """

def q_one(self, sql: str, params: Dict = None) -> Optional[Dict]: ...
    """
    Execute a statement and return the first result.
    If there are no results, return `None`.
    """

def q_val(self, sql: str, params: Dict = None) -> Any: ...
    """
    Execute a statement and return the value in the first column of the first result.
    If there are no results, return `None`.
    """

Each fort database class instance also has a logger at self.log:

    db = MyDatabase('postgres://user:password@host/database')
    db.log.info('Hello from my database class instance!')

Notes on specific database classes

PostgresDatabase

Use PostgresDatabase to connect to a PostgreSQL database. Use pyformat paramstyle for all your statements. Your connection string will be passed directly to psycopg2.connect().

You are still responsible for installing psycopg2.

SQLiteDatabase

Use SQLiteDatabase to connect to an SQLite database. Use named paramstyle for all your statements. Your connection string will be passed directly to sqlite3.connect().