Creating indexed nodes on neo4j cypher via rest api

Question

I'm trying to create an indexed node in cypher, with the following syntax:

neo4j-sh (?)$ start m=node:person(UID= "1")  return m;
==> +------------+
==> | m          |
==> +------------+
==> | Node[64]{} |
==> +------------+
==> 1 row
==> 0 ms
==> 
neo4j-sh (?)$ start n = node(64) return n.UID;
==> EntityNotFoundException: The property 'UID' does not exist on Node[64]

Why is it that the node appears to be created, but the property I'm creating, and that seems to be successfully returned, does not exist?

Is there an easier way? I used to use py2neo's function:

neo4j.GraphDatabaseService("http://localhost:7474/db/data/").get_or_create_indexed_node(index='person', key='UID', value=self.id, properties={'UID' : self.id})

But this appears to have been deprecated---it no longer works with the latest version of py2neo, which does not appear to support the properties argument any longer (and for future folks, index is replaced with index_name).

MrDosu · Accepted Answer · 2013-04-18T14:50:32.557

2

An index and a property are two different things.

It seems you have a node in your graph with an index named person and key/value pair UID:"1". Your first query gets your node by its index. But the index is not a property of the node. You can fire up the webadmin to visualize how the indices are managed in your graph.

As far as i know there is nothing in the documentation on how to create indices with cypher, but you can easily use the REST API to manipulate them (link).

edited Apr 18 '13 at 14:50

answered Apr 18 '13 at 13:25

MrDosu

3,427
15
18

Isn't the index "person," as given by `start n node:/person/`? The properties are defined in parens after. Py2neo uses the REST API under the hood to have created the index. – Mittenchops Apr 18 '13 at 13:50
Yes, the above query uses the index named person looking up the key/value pair UID:"1". While in practice the key/value pairs are often created to reflect node properties this is not necessary as far as i know. If you look at the REST index documentation (http://docs.neo4j.org/chunked/stable/rest-api-indexes.html) you can easily create key/value indices that have nothing to do with the nodes properties. – MrDosu Apr 18 '13 at 14:48
I think I don't understand---are you saying my syntax is not creating a key/value on an index, or not creating a node at all, or not creating a property on an indexed node? – Mittenchops Apr 18 '13 at 16:45
I mean the cypher statement is just a query. What you want to do is CREATE UNIQUE (http://assets.neo4j.org/download/Neo4j_CheatSheet_v3.pdf), but i dont know if you can index nodes at all with cypher (unless auto indexing). – MrDosu Apr 19 '13 at 10:10

score 1 · Answer 2 · answered Apr 19 '13 at 06:10

The method has not been deprecated and the properties argument is still valid, as before. The only change, as you identify, is the change from index to index_name for the first argument.

The documentation is here:

http://book.py2neo.org/en/latest/graphs_nodes_relationships.html#py2neo.neo4j.GraphDatabaseService.get_or_create_indexed_node

Note that the properties will only actually be used when the node does not already exist, i.e. when doing a 'create' but not when doing a 'get'. Otherwise, the existing node will remain as-is.

Creating indexed nodes on neo4j cypher via rest api

2 Answers2