orm.py

A small ORM for Python.

Features

• Basic queries (select, insert, update, order by, limit, offset)
• Simple model interace with foreign keys

Not Features

• Database or table creation, modification, or migration
• Joins, full text search, most other database features

Requirements

• python3
• postgresql
• psycopg2

To do

• python2 support
• better comparison support
• only update fields that have changed
• order by with get
• query unique entries
• tests
• improve query interface
• expand sql functionality

Example

Tables are not created for you, so you must create them yourself. Table names should match the class name when converted to underscore- separated words, so a class UserRelationship will map to the table "user_relationship".

Tables must have a serial primary key called "id", and foreign key fields must be appended with "_id".

import orm

''' You should first set up tables named "user" and "message" '''
class User(orm.Model):
    username = orm.Field()
    password = orm.Field()

    def get_all_received_messages(self):
        ''' You could also pass in a limit and offset, or yield results
            one at a time.
        '''
        return list(Message.all(user_to=self, order_by='-date_sent'))

    def get_all_sent_messages(self):
        return list(Message.all(user_from=user, order_by='-date_sent'))

class Message(orm.Model):
    user_from = orm.ForeignKey(User) # field should be named "user_from_id"
    user_to = orm.ForeignKey(User) # field should be named "user_to_id"
    date_sent = orm.Field()
    body = orm.Field()
    read = orm.Field(default=False)        

Now you can make queries in a script or interpreter:

u = User.get(id=1)
m = list(Message.all(user_from=u))

API

user.save()

Saves or updates a Model object.

user.delete()

Deletes the Model object. Any cascades must be done in table definitions.

Model.get(id=None, **kwargs)

Pass in the ID or kwargs matching your model fields.

Model.all(separator='AND', order_by=None, limit='ALL', offset=None, **kwargs):

all yields the results, so you must catch them in a loop or list.

• separator: pass in 'OR' and a kwarg with a list of possible arguments. For example:

  Message.all(separator='OR', user_from=[user_1, user_2])

This will match all messages from either user_1 or user_2.

• order_by: pass in a string with a field name. Prepend '-' to reverse the order.

• limit: Limit results to first n results.

• offset: Integer to offset your search result

• kwargs: each kwarg value can be a single object or a list.

  Model.count(**kwargs)

Returns an integer.

Model.is_unique(**kwargs)

Returns True or False.