Neo4J Graph Algorithms Cypher Projection should return only numbers?

Question

Hello I make a Graph Algorithm Neo4J request in Cypher of the following kind, which first finds the nodes and then the relations between them:

CALL algo.pageRank.stream('MATCH (u:User{uid:"0ee14110-426a-11e8-9d67-e79789c69fd7"}), 
(ctx:Context{name:"news180417"}), (u)<-[:BY]-(c:Concept)-[:AT]->(ctx) 
RETURN DISTINCT id(c) as id', 
'CALL apoc.index.relationships("TO","user:0ee14110-426a-11e8-9d67-e79789c69fd7") 
YIELD rel, start, end WITH DISTINCT rel, start, end MATCH (ctx:Context) 
WHERE rel.context = ctx.uid AND (ctx.name="news180417" ) 
RETURN DISTINCT id(start) AS source, id(end) AS target', 
{graph:'cypher', iterations:5});

Which works fine. However, when I try to return c.uid instead of its Neo4J id() the Graph Algorithms don't accept it.

Does it mean I can only operate using Neo4J ids in Graph Algorithms?

What is the error given by Graph Algorithms that indicates that it does not accept c.uid? — Rebecca Nelson
It sounds like the library will not allow you to call a MATCH pattern that returns a non-int. — Rebecca Nelson
Ah, sorry, it looks like I misinterpreted you. If the question is that "given this library says I can't return a String, can I return a string?" the answer is of course, "no, that is not possible". Are you looking for an alternate invocation or library that can accept label as a string value for PageRank? — Rebecca Nelson

cybersam cybersam · Accepted Answer · 2018-04-18T00:08:30

When you use Cypher projection with the Graph Algorithms procedures, you pass 2 Cypher statements (and a config map).

The first Cypher statement must return an id variable whose value is the native ID of a node.

The second Cypher statement must return source and target variables whose values are also node IDs.

So, yes, your Cypher statements must always return neo4j native IDs.

Neo4J Graph Algorithms Cypher Projection should return only numbers?

1 Answers