deni64k/remodel

Very simple yet powerful and extensible Object Document Mapper for RethinkDB, written in Python.

remodel

Very simple yet powerful and extensible Object Document Mapper for RethinkDB, written in Python.

It is plain simple!

from remodel.models import Model

class User(Model):
    pass

That's really everything you need to do to set up a model!

Don't forget to turn on your RethinkDB server and to create your tables (check the examples below for a helper that does just that!).

Features

• schemaless;
• dict interface;
• full support for relations;
• indexes;
• convention over configuration;
• lazy-loading;
• caching;

Installation

pip install remodel

Examples

Basic CRUD operations

class Order(Model):
    pass

# Create
my_order = Order.create(customer='Andrei', shop='GitHub')
# Update
my_order['total'] = 100
my_order.save()
# Read
saved_order = Order.get(customer='Andrei')
# Delete
saved_order.delete()

Creating tables

from remodel.models import Model
from remodel.utils import create_tables, create_indexes

class Party(Model):
    has_many = ('Guest',)

class Guest(Model):
    belongs_to = ('Party',)

# Creates all database tables defined by models
create_tables()
# Creates all table indexes based on model relations
create_indexes()

Relations

Has one / Belongs to

class User(Model):
    has_one = ('Profile',)

class Profile(Model):
    belongs_to = ('User',)

andrei = User.create(name='Andrei')
profile = Profile.create(user=andrei, network='GitHub', username='linkyndy')
print profile['user']['name'] # prints Andrei

Has many / Belongs to

class Country(Model):
    has_many = ('City',)

class City(Model):
    belongs_to = ('Country',)

romania = Country.create(name='Romania')
romania['cities'].add(City(name='Timisoara'), City(name='Bucharest'))
print romania['cities'].count() # prints 2

Has and belongs to many

class Post(Model):
    has_and_belongs_to_many = ('Tag',)

class Tag(Model):
    has_and_belongs_to_many = ('Post',)

my_post = Post.create(name='My first post')
personal_tag = Tag.create(name='personal')
public_tag = Tag.create(name='public')
my_post['tags'].add(personal_tag, public_tag)
print my_post['tags'].count() # prints 2

Has many through

class Recipe(Model):
    has_many = ('SpecificSpice',)

class Chef(Model):
    has_many = ('SpecificSpice',)

class SpecificSpice(Model):
    belongs_to = ('Recipe', 'Chef')

quattro_formaggi = Recipe.create(name='Pizza Quattro Formaggi')
andrei = Chef.create(name='Andrei')
andreis_special_quattro_formaggi = SpecificSpice.create(chef=andrei, recipe=quattro_formaggi, oregano=True, love=True)
print andreis_special_quatro_formaggi['love'] # prints True

Custom model queries

import rethinkdb as r

class Celebrity(Model):
    pass

Celebrity.create(name='george clooney')
Celebrity.create(name='kate winslet')
upper = Celebrity.map({'name': r.row['name'].upcase()}).run()
print list(upper) # prints [{u'name': u'GEORGE CLOONEY'}, {u'name': u'KATE WINSLET'}]

Custom instance methods

class Child(Model):
    def is_minor(self):
        if 'age' in self:
            return self['age'] < 18

jack = Child.create(name='Jack', age=15)
jack.is_minor() # prints True

Custom class methods

from remodel.object_handler import ObjectHandler, ObjectSet

class TripObjectHandler(ObjectHandler):
    def in_europe(self):
        return ObjectSet(self, self.query.filter({'continent': 'Europe'}))

class Trip(Model):
    object_handler = TripObjectHandler

Trip.create(continent='Europe', city='Paris')
Trip.create(continent='Asia', city='Shanghai')
Trip.create(continent='Europe', city='Dublin')
print len(Trip.in_europe()) # prints 2

Viewing object fields

class Train(Model):
    pass

train = Train.create(nr=12345, destination='Paris', has_restaurant=True, classes=[1, 2])
print train.fields.as_dict()
# prints {u'classes': [1, 2], u'nr': 12345, u'destination': u'Paris', u'has_restaurant': True, u'id': u'd9b8d57f-5d67-4ff7-acf8-cbf7fdd65581'}

Concepts

Relations

Remodel supports various types of relationships:

• has one
• belongs to
• has many
• has and belongs to many
• has many through

Defining relations

Related models are passed as tuples in a model's definition. All other aspects, such as foreign keys, indexes, lazy relation loading and relation cache are magically handled for you.

If you need precise definition for your related models, you can pass a configuration tuple instead of the string name of your related model:

    class Artist(Model):
        has_many = (('Song', 'songs', 'id', 'song_id'), 'Concert')
        # Tuple definition: (<related model name>, <related objects accessor field>, <model key>, <related model key>)

One important thing to notice is that reverse relationships are not automatically ensured if only one end of the relationship is defined. This means that if Artist has_many Song, Song belongs_to Artist is not automatically enforced unless explicitly defined.

Using relations

Assigning has_one and belongs_to objects doesn't mean that they are persisted. You need to manually call save() on them; assuming Profile belongs_to User:

profile['user'] = User(...)
profile.save()

On the other side, assigning has_many and has_and_belongs_to_many objects automatically persist them, so there is no need for you to call save() on them; assuming Shop has_many Product:

shop.add(product1, produt2)
# No need to call save() on products!

Note that certain assignments of related objects can not be performed unless one (or both) of the objects is saved. You can not save a GiftSize with a Gift attached without saving the Gift object first (when having a GiftSize belongs_to Gift).

Motivation

The main reason for Remodel's existence was the need of a light-weight ODM for RethinkDB, one that doesn't force you to ensure a document schema, one that provides a familiar interface and one that gracefully handles relations between models.

Development

Remodel is under active development and it is not yet production-ready. Any contribution is highly appreciated, no matter it is a small bug fix, feature implementation or a typo in the docs.

How to contribute

Just fork this repository, do your magic and submit a pull request on the development branch!

Branches

Active development and up-to-date code can be found on the develop branch

Stable code can be found on the master branch

Running tests

pip install pytest
py.test tests/

Tracking issues

All Remodel issues/feature requests/bugs/questions can be addressed on https://github.com/linkyndy/remodel/issues