Neo4j Same Entity Relationship persistence issue - neo4j

Question

Is is possible to pls advice me how to go about.. doing a Same Entity Relationship..
For ex.
Entity(class Person) relatesTo Entity(class Person).
CODE:
#NodeEntity
public class Person
{
#GraphId #GeneratedValue
private Long id;
#Indexed(indexType = IndexType.FULLTEXT, indexName = "searchByPersonName")
private String personName;
#Fetch #RelatedTo(type = "CONNECTS_TO", direction = Direction.BOTH)
private Set<ConnectedPersons> connectedPersons;
public ConnectedPersons connectsTo(Person endPerson, String connectionProperty)
{
ConnectedPersons connectedPersons = new ConnectedPersons(this, endPerson, connectionProperty);
this.connectedPersons.add(connectedPersons); //Null Pointer Here(connectedPersons is null)
return connectedPersons;
}
}
CODE:
#RelationshipEntity(type = "CONNECTED_TO")
public class ConnectedPersons{
#GraphId private Long id;
#StartNode private Person startPerson;
#EndNode private Person endPerson;
private String connectionProperty;
public ConnectedPersons() { }
public ConnectedPersons(Person startPerson, Person endPerson, String connectionProperty) { this.startPerson = startPerson; this.endPerson = endPerson; this.connectionProperty = connectionProperty;
}
I am trying to have a Relationship to the same class.. i.e. Persons connected to the Person.. When I invoke a Junit test :
Person one = new Person ("One");
Person two = new Person ("Two");
personService.save(one); //Works also when I use template.save(one)
personService.save(two);
Iterable<Person> persons = personService.findAll();
for (Person person: persons) {
System.out.println("Person Name : "+person.getPersonName());
}
one.connectsTo(two, "Sample Connection");
template.save(one);
I get Null pointer when I try to do one.connectsTo(two, "Prop");
Please could you tell where am I going wrong?
Thanks in advance.

Answer 1

One other thing besides the missing initialization of the Set is that the class ConnectedPersons is a #RelationshipEntity. But in your class Person you are using it with the #RelatedTo annotation as if it were a #NodeEntity. You should use the #RelatedToVia annotation in the Person class instead.

Answer 2

You are getting null pointer exception in the below code because you haven't initialized the connectedPersons collection.
this.connectedPersons.add(connectedPersons); //Null Pointer Here(connectedPersons is null)
Initialize the collection as shown below
#Fetch #RelatedTo(type = "CONNECTS_TO", direction = Direction.BOTH)
private Set<ConnectedPersons> connectedPersons=new HashSet<ConnectedPersons>();