How to persist a List<CustomObject> as a property of a node? - neo4j

Question

I am trying to persist a list of objects of a class suppose xyz. when I do this in the NodeEntity Class:
#Property
List<xyz> listOfConditions
The Node table when loaded from the neo4j-database via the Neo4jOperations.load(entity) method, will return an error saying :- ERROR mapping GraphModel to NodeEntity type class.
Is there any way to persist a List of Objects onto a nodes properties in Neo4j?. I am using neo4j-ogm-embedded driver and Spring-data-neo4j.

Answer 1

Neo4j does not support storing another object as a nested property. Neo4j-OGM only supports
any primitive, boxed primitive or String or arrays thereof,
essentially anything that naturally fits into a Neo4j node property.
If you want to work around that, you may need to create a custom type convertor. For example,
import org.neo4j.ogm.typeconversion.AttributeConverter
class XYZ{
XYZ(Integer x, String y) {
this.x = x
this.y = y
}
Integer x
String y
}
public class XYZConverter implements AttributeConverter<XYZ, String> {
#Override
public String toGraphProperty(XYZ value) {
return value.x.toString() + "!##" + value.y
}
#Override
public XYZ toEntityAttribute(String value) {
String[] split = value.split("!##")
return new XYZ(Integer.valueOf(split[0]), split[1])
}
}
You can then annotate the #NodeEntity with a #Convert like this
#NodeEntity
class Node {
#GraphId
Long id;
#Property
String name
#Convert(value = XYZConverter.class)
XYZ xyz
}
On the flip side, its not a good practice to do this, since ideally you should link Node and XYZ with a 'hasA' relationship. Neo4j has been designed to optimally handle such kind of relationships, so it would be best to play with to strengths of neo4j

Answer 2

No, nested objects represented as properties on a single node are not supported by the OGM. The only option is to write a custom converter to serialize the nested object to a String representation and store it as a single property.
Otherwise, a list of objects on a node is treated as relationships from the node to those objects.
Here's a link to the manual for further reference: http://neo4j.com/docs/ogm-manual/current/