Peewee ORM

Peewee ORM
Original author(s) Charles Leifer[1]
Initial release October 11, 2010[2]
Stable release 2.4.5 / December 21, 2014
Development status Active
Written in Python
Operating system Cross-platform
Type Object-relational mapping
License MIT License
Website www.peewee-orm.com

Peewee is an open source object-relational mapper (ORM) for the Python programming language released under the MIT License.

Peewee provides a lightweight, expressive Python API for interacting with relational databases. Peewee follows the active record pattern used by a number of other object-relational mappers. Peewee supports PostgreSQL, MySQL and SQLite and has many database-specific extensions included in the Playhouse collection of add-ons.

Peewee was first released on October 11, 2010.[2] In October 2012, Peewee was completely rewritten and version 2.0 was released.[3]

Example

The following example represents an n-to-1 relationship between people and their status updates. It shows how user-defined Python classes are mapped to database tables, and how to execute common database queries.

Schema definition

Creating two Python classes and according database tables in the DBMS:

from peewee import *
 
db = SqliteDatabase('app.db')
 
class BaseModel(Model):
    class Meta:
        database = db
 
class Person(BaseModel):
    name = CharField(max_length=100, index=True)
 
class StatusUpdate(BaseModel):
    person = ForeignKeyField(Person, related_name='statuses')
    status = TextField()
    timestamp = DateTimeField(default=datetime.datetime.now, index=True)
 
Person.create_table()
StatusUpdate.create_table()

Data insertion

Inserting people and their status updates:

# New rows can be added by creating an instance and calling save():
huey = Person(name='Huey')
huey.save()
 
# Or the create() method can be used:
charlie = Person.create(name='Charlie')
 
StatusUpdate.create(person=charlie, status='Hello, world')
StatusUpdate.create(person=charlie, status='Hello, peewee')
 
# Using a transaction.
with db.transaction():
    StatusUpdate.create(person=huey, status='Hello')

Querying 

people = Person.select().order_by(Person.name)
for person in people:
    print person.name
    for status in person.statuses.order_by(StatusUpdate.timestamp):
        print '*', status.status

The output:

Charlie
* Hello, world
* Hello, peewee
Huey
* Hello

Performing a join:

charlie_statuses = (StatusUpdate
                    .select(StatusUpdate, Person)
                    .join(Person)
                    .where(Person.name == 'Charlie')
                    .order_by(StatusUpdate.timestamp.desc()))
for status in charlie_statuses:
    print status.person.name, '-', status.status

The output:

Charlie - Hello, peewee
Charlie - Hello, world

Features

See also

References

  1. ↑ Charles Leifer is the creator of peewee ORM.
  2. ↑ 2.0 2.1 Leifer, Charles (October 11, 2010). "[ANN] Peewee 0.1". Peewee. Retrieved October 11, 2010.
  3. ↑ Leifer, Charles (October 8, 2012). "[ANN] Peewee 2.0". Peewee. Retrieved October 8, 2012.

External links