Compute.is_reachable()#

#Compute.is_reachable(node1: Producer, node2: Producer) -> Expression

#import relationalai as rai
from relationalai.std import alias
from relationalai.std.graphs import Graph

# Create a model named "socialNetwork" with a Person type.
model = rai.Model("socialNetwork")
Person = model.Type("Person")

# Add some people to the model and connect them with a multi-valued `follows` property.
with model.rule():
    alice = Person.add(name="Alice")
    bob = Person.add(name="Bob")
    carol = Person.add(name="Carol")
    alice.follows.add(bob)
    bob.follows.add(carol)

# Create a directed graph with Person nodes and edges between followers.
# Note that graphs are directed by default.
# This graph has edges from Alice to Bob and Bob to Carol.
graph = Graph(model)
graph.Node.extend(Person)
graph.Edge.extend(Person.follows)

# Can Alice reach Carol?
with model.query() as select:
    alice = Person(name="Alice")
    carol = Person(name="Carol")
    with model.match() as reachable:
        with model.case():
            graph.compute.is_reachable(alice, carol)
            reachable.add(True)
        with model.case():
            reachable.add(False)
    response = select(alias(reachable, "is_reachable"))

print(response.results)
# Output:
#    is_reachable
# 0          True

# Who can reach Alice?
with model.query() as select:
    person = Person()
    graph.compute.is_reachable(person, Person(name="Alice"))
    response = select(person.name)

# The only person that can reach Alice is herself.
print(response.results)
# Output:
#   name
# 0 Alice