Py2neo V3 adding relationships to transactions in a loop - neo4j

Question

Trying to add nodes and relationships in transactional manner using py2neo V3.
I would like to add the person and all their movies as one transaction.
I could not get nodes in the outer and inner loops to work in the same transaction. I'm pretty confident the relationship is not being added in a transactional manner either since I'm calling tx1.graph.
Neo4j V3.0.7
Py2Neo v3.1.2
from py2neo import Graph,Node,Relationship,authenticate, watch
from py2neo.ogm import GraphObject, Property, RelatedTo, RelatedFrom
class Movie(GraphObject):
__primarykey__ = "title"
title = Property()
class Person(GraphObject):
__primarykey__ = "name"
name = Property()
acted_in = RelatedTo(Movie)
People = ["John","Jane","Tarzan"]
Movies = [["John","Movie1"],["John","Move2"],["Jane","Movie3"],["Jane","Movie4"],["Tarzan","Movie4"]]
graph = Graph("http://localhost:7474")
for p in People:
print(p)
tx = graph.begin()
p1 = Person()
p1.name = p
tx.merge(p1)
tx.commit()
for m in Movies:
if m[0] != p:
continue
print(m[1])
tx1 = graph.begin() #did not work using original tx transaction
m1 = Movie()
m1.title = m[1]
tx1.merge(m1)
p1.acted_in.add(m1)
#tx1.merge(p1) #did not create relationship
#tx1.create(p1) #did not create relationship
tx1.graph.push(p1) # worked in adding relationship, but can't guarantee was part of the transaction
tx1.commit()

Answer 1

Try the following loop, which uses a single transaction for each Person and its relationships:
for p in People:
print(p)
tx = graph.begin()
p1 = Person()
p1.name = p
tx.merge(p1)
for m in Movies:
if m[0] != p:
continue
print(m[1])
m1 = Movie()
m1.title = m[1]
tx.merge(m1)
p1.acted_in.add(m1)
tx.graph.push(p1)
tx.commit()
Note: It would actually be more efficient to use a single transaction for processing multiple persons. But you would not want to handle too many (depending on your data model) at one time either, as that would risk making the server run out of memory.