a little orm
Project description
peewee
a small orm
written in python
provides a lightweight querying interface over sql
uses sql concepts when querying, like joins and where clauses
supports sqlite, mysql and postgresql
support for special extensions like hstore and full-text search
For flask integration, including an admin interface and RESTful API, check out flask-peewee.
For notes on the upgrade from 1.0 to 2.0, check out the upgrade docs.
Examples:
# a simple query selecting a user
User.get(User.username == 'charles')
# get the staff and super users
editors = User.select().where(
(User.is_staff == True) |
(User.is_superuser == True)
)
# get tweets by editors ("<<" maps to IN)
Tweet.select().where(Tweet.user << editors)
# how many active users are there?
User.select().where(User.active == True).count()
# paginate the user table and show me page 3 (users 41-60)
User.select().order_by(User.username).paginate(3, 20)
# order users by number of tweets
User.select().annotate(Tweet).order_by(
fn.Count(Tweet.id).desc()
)
# a similar way of expressing the same
User.select(
User, fn.Count(Tweet.id).alias('ct')
).join(Tweet).group_by(User).order_by(R('ct desc'))
# do an atomic update
Counter.update(count=Counter.count + 1).where(
Counter.url == request.url
)
Learning more
the official peewee cookbook has recipes for common operations and is a good place to get started.
check the documentation for more examples.
specific question? come hang out in the #peewee channel on freenode.irc.net, or post to the mailing list, http://groups.google.com/group/peewee-orm
lastly, peewee runs on python 2.5 or greater, though there is currently no support for python3
Still want more info?
Why?
peewee began when I was working on a small app in flask and found myself writing lots of queries and wanting a very simple abstraction on top of the sql. I had so much fun working on it that I kept adding features. My goal has always been, though, to keep the implementation incredibly simple. I’ve made a couple dives into django’s orm but have never come away with a deep understanding of its implementation. peewee is small enough that its my hope anyone with an interest in orms will be able to understand the code without too much trouble.
model definitions and schema creation
smells like django:
import peewee
class Blog(peewee.Model):
title = peewee.CharField()
def __unicode__(self):
return self.title
class Entry(peewee.Model):
title = peewee.CharField(max_length=50)
content = peewee.TextField()
pub_date = peewee.DateTimeField()
blog = peewee.ForeignKeyField(Blog)
def __unicode__(self):
return '%s: %s' % (self.blog.title, self.title)
gotta connect:
>>> from peewee import database >>> database.connect()
create some tables:
>>> Blog.create_table() >>> Entry.create_table()
foreign keys work like django’s
>>> b = Blog(title="Peewee's Big Adventure") >>> b.save() >>> e = Entry(title="Greatest movie ever?", content="YES!", blog=b) >>> e.save() >>> e.blog <Blog: Peewee's Big Adventure> >>> for e in b.entry_set: ... print e.title ... Greatest movie ever?
querying
queries come in 4 flavors (select/update/insert/delete).
there’s the notion of a query context which is the model being selected or joined on:
User.select().where(User.active == True).order_by(User.username)
since User is the model being selected, the where clause and the order_by will pertain to attributes on the User model. User is the current query context when the .where() and .order_by() are evaluated.
an example using joins:
Tweet.select().join(User).where(
(Tweet.deleted == False) & (User.active == True)
).order_by(Tweet.pub_date.desc())
this will select non-deleted tweets from active users.
using sqlite
import peewee
database = peewee.SqliteDatabase('my.db')
class BaseModel(peewee.Model):
class Meta:
database = database
class Blog(BaseModel):
creator = peewee.CharField()
name = peewee.CharField()
class Entry(BaseModel):
creator = peewee.CharField()
name = peewee.CharField()
using postgresql
you can now use postgresql:
import peewee
database = peewee.PostgresqlDatabase('my_db', user='root')
class BaseModel(peewee.Model):
class Meta:
database = database
# ... same as above sqlite example ...
using mysql
you can now use MySQL:
import peewee
database = peewee.MySQLDatabase('my_db', user='root')
class BaseModel(peewee.Model):
class Meta:
database = database
# ... same as above sqlite example ...
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