peewee 0.1.0

a little orm

a small orm

written to provide a lightweight querying interface over sql

uses sql concepts when querying, like joins, group by, having, etc.

Examples:

# a simple query selecting a user
User.select().where(username='charles')

# get the tweets by a user named charles and order the newest to oldest
Tweet.select().order_by(('pub_date', 'desc')).join(User).where(username='charles')

# how many active users are there?
User.select().where(active=True).count()

# paginate the user table and show me page 3 (users 41-60)
User.select().order_by(('username', 'asc')).paginate(3, 20)

# order users by number of tweets
User.select({
    User: ['*'],
    Tweet: [Count('id', 'num_tweets')]
}).group_by('id').join(Tweet).order_by(('num_tweets', 'desc'))

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(active=True).order_by(('username', 'asc'))

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().where(deleted=False).order_by(('pub_date', 'desc')).join(
    User
).where(active=True)

this will select non-deleted tweets from active users. the first .where() and .order_by() occur when Tweet is the current query context. As soon as the join is evaluated, User becomes the query context and so the following where() pertains to the User model.