kaiso 0.13.3

A queryable object persistence and relationship framework based on the Neo4j graph database.

A graph based queryable object persistance framework built on top of Neo4j.

Build status

Example

In addition to objects, Kaiso also stores the class information in the graph. This allows us to use cypher to query instance information, but also to answer questions about our types.

Let’s define some basic classes

from kaiso.attributes import Integer, Outgoing, String, Uuid
from kaiso.types import Entity, Relationship


# define a simple type hierarchy

class Knows(Relationship):
    pass


class Animal(Entity):
    id = Uuid(unique=True)
    name = String()
    knows = Outgoing(Knows)


class Carnivore(Animal):
    pass


class Herbivore(Animal):
    pass


class Penguin(Herbivore):
    favourite_ice_cream = String()


class Lion(Carnivore):
    n_siblings = Integer()

As with any orm, we can make some instances and persist them in our graph

from kaiso.persistence import Manager

manager = Manager("http://localhost:7474/db/data/")


# create some instances

fred = Penguin(name="Fred")
tom = Lion(name="Tom")

relation = Knows(fred, tom)

manager.save(fred)
manager.save(tom)
manager.save(relation)

Using the Neo4j web interface to explore our graph, we find Tom and Fred:

However, in addition, we can also see the type information in the graph:

We can make use of the type information in our queries, e.g. to find all herbivores who know a carnivore

START
    Herbivore=node:persistabletype(id="Herbivore"),
    Carnivore=node:persistabletype(id="Carnivore")

MATCH
    Carnivore <-[:ISA*]-()<-[:INSTANCEOF]-(carnivore),
    Herbivore <-[:ISA*]-()<-[:INSTANCEOF]-(herbivore),

    (herbivore)-[:KNOWS]->(carnivore)

RETURN
    "The herbivore",
    herbivore.name,
    "knows the carnivore",
    carnivore.name;

==> +---------------------------------------------------------------------+
==> | "The herbivore" | "Fred"      | "knows the carnivore" | "Tom"       |
==> +---------------------------------------------------------------------+