Model Objects

Warning

This is the first iteration of the interface for model objects. The function/class signatures might change in the next releases.

Basic Usage

Creating NodeSet and RelationshipSet classes with string is error prone.

Graphio offers a simple object graph model system:

from graphio import ModelNode, ModelRelationship

class Person(ModelNode):
    name = MergeKey()

class Food(ModelNode):
    type = MergeKey()

class PersonLikes(ModelRelationship):
    source = Person
    target = Food
    type = 'LIKES'

You can use these classes to create NodeSet and RelationshipSet:

person_nodeset = Person.dataset()
food_nodeset = Food.dataset()

person_likes_food = PersonLikes.dataset()

When adding data to the RelationshipSet you can use the MergeKey properties of the ModelNode classes to avoid typing the properties as strings:

for name, food in [('Susan', 'Pizza'), ('Ann', 'Sushi')]:
    person_likes_food.add_relationship(
        {Person.name: name}, {Food.type: food}
    )

You can set one or multiple Label and MergeKey properties on the ModelNode:

class Person(ModelNode):
    first_name = MergeKey()
    last_name = MergeKey()

    Person = Label()
    Human = Label()

You can override the actual values of the Label and MergeKey:

class Person(ModelNode):
    first_name = MergeKey('first_name')
    last_name = MergeKey('surname')

    Person = Label('Individual')
    Human = Label('HomoSapiens')

Add data with model instances

You can create instances of the model objects to create individual nodes and relationships:

from graphio import ModelNode, ModelRelationship
from py2neo import Graph

graph = Graph()

class Person(ModelNode):
    name = MergeKey()

class Food(ModelNode):
    type = MergeKey()

class PersonLikes(ModelRelationship):
    source = Person
    target = Food
    type = 'LIKES'

alice = Person(name='Alice')
sushi = Food(type='Sushi')

alice.merge(graph)
sushi.merge(graph)

alice_likes_sushi = PersonLikes(alice, sushi)
alice_likes_sushi.merge(graph)

You can also link nodes without creating ModelRelationship instances:

alice.link(graph, PersonLikes, sushi, since='always')

ModelNode

class graphio.ModelNode(*args, **kwargs)

Baseclass for model objects.

additional_props

Return all properties except the merge properties.

Returns:Dictionary with all properties except the merge properties. Return type:dict

classmethod dataset() → graphio.objects.nodeset.NodeSet

Returns:Return a NodeSet instance for this ModelNode.

classmethod factory(labels: List[str], merge_keys: List[str] = None, name: str = None) → type

Create a class with given labels and merge_keys. The merge_keys are optional but some functions do not work without them.

Parameters:

• labels – Labels for this ModelNode class.
• merge_keys – MergeKeys for this ModelNode class.

Returns:

The ModelNode class.

merge_props

Return the merge properties for this node.

Returns:Dictionary with the merge properties for this node. Return type:dict

ModelRelationship

class graphio.ModelRelationship(source: graphio.model.ModelNode, target: graphio.model.ModelNode, **kwargs)

Base class for model relationships.

Knows about the class of source node and target node (instances of ModelNode) and the relationship type:

class Person(ModelNode):
    name = MergeKey()

class Food(ModelNode):
    name = MergeKey()

class PersonLikesToEat(ModelRelationship):
    source = Person
    target = Food
    type = 'LIKES'

classmethod dataset() → graphio.objects.relationshipset.RelationshipSet

Returns:Return a RelationshipSet instance for this ModelRelationship.

Helper Classes

class graphio.NodeDescriptor(labels: List[str], properties: dict, merge_keys: List[str] = None)

Unified interface to describe nodes with labels and properties.

NodeDescriptor instances are passed into functions when no ModelNode classes or instances are available.

Setting merge_keys is optional. If they are not set all property keys will be used as merge_keys.

Parameters:

• labels – Labels for this node.
• properties – Properties for this node.
• merge_keys – Optional.