Spring Data Neo4j: How to map java.util.Map<String,String> field?

[vmarcinko]

Hello,

I have an relationship node class like this :

@RelationshipNode
public class MyConnection {
private String title;
private long duration;
private Map<String,String> attributes;
...
}

When using Spring data Neo4J mapping layer, it naturally creates relationship nodes in Neo4j with keys "title" and "duration" corresponding to names of my class fields, but Map<String,String> field is not persisted. I would like those key-value entries in this Map to be also persisted inside this relationship node also as list of properties, but I understand the problem that I would have to distinguish this map field from other fields.

I could decide for eg. to add additional prefix, something like "fieldName_" + entry.getKey() for name of property.
Is it possible somehow to add some loading/saving interceptor in Spring-Data-Neo4j lib so it can work when loading/persisting this class insatnces, or it's not possible so I would have to use low-level Neo4 API for that (Neo4JTemplate)? I don't like later because I don't know how elegant it would be to mix those two approaches in my application.

Regards,
Vjeran

[MichaelHunger]

You would use the DynamicProperties instead of the Map which is then mapped to node-attributes.

See this test, on how to use it.

@NodeEntity
public class Person {
    @GraphId
	private Long graphId;

	private DynamicProperties personalProperties;
	public void setProperty(String key, Object value) {
		personalProperties.setProperty(key, value);
	}

	public Object getProperty(String key) {
		return personalProperties.getProperty(key);
	}
}
@Test
    public void testCreateOutsideTransaction() {
        Person p = new Person("James", 35);
        p.setProperty("s", "String");
        p.setProperty("x", 100);
        p.setProperty("pi", 3.1415);
        persist(p);
        assertEquals(3, IteratorUtil.count(p.getPersonalProperties().getPropertyKeys()));
        assertProperties(nodeFor(p));
        p.setProperty("s", "String two");
        persist(p);
        assertEquals("String two", nodeFor(p).getProperty("personalProperties-s"));
    }

[vmarcinko]

Oh, great!
Thanx.

[vmarcinko]

I noticed a shortcoming with current way of persisting DynamicProperties - this map entries are stored with property names constructed with prefix (derived from DynamicProperties field name) and map key, separated by dash ("-"), and since dash is a special character inside Cypher, it is not simply possible to query these node properties by using query piece such as:

node.prefix-mapkey

, but one has to use quite unknown "backtick" character for quoting node property name, such as:

node.`prefix-mapkey`

Therefore, I would suggest that separation character is underscore, which is not treated as special character as I know.

Regards,
Vjeran

[MichaelHunger]

Good point,

can you raise an JIRA issue? for that

Better to make it configurable

Michael