Maximum Number of Relationships

[ghost]

It would be nice to define the number of relationships that can exist between two types of nodes. Not only for uniqueness, but also for logic.

class Sedan(StructuredNode):
    seat = RelationshipFrom('SEAT', 'INCLUDED_IN', max_rels=4)
    # this sedan can have up to 4 seats

class Person(StructuredNode):
    car = RelationshipFrom('CAR', 'OWNED_BY', max_rels=1)
    # this car can only have up to 1 owner

class Router(StructuredNode):
    devices = RelationshipFrom('ROUTER', 'CONNECTED_TO', max_rels=30)

I am aware that I could do this easily enough in application logic with simple if statements, but it would be nice not to have to write them. I keep winding up with these duplicate relationships when things slip through in testing.

I suppose I'm just scared to dive into the world of open source contribs =\

[aanastasiou]

Not exactly helping but this is a Multiplicity constraint and the foundation for doing this is already there in StructuredRel via Cardinality. It is a matter of adding the constrain checks.