Neo4j Scalar functions in c#

Question

In Neo4j we can do: startNode(relationship), endNode(relationship) and it will give us the start and end of the node given a relationship.

My sample query is this:

match p=(n1 {Identifier:<id>})-[:r1|r2*2]-(n2) unwind relationships(p) as rel return distinct startNode(rel) as n1, type(rel), endNode(rel) as n2

so Basically its a variable length relationships and I can get the type, as well as the start and end node of each relationship.

If I don't specify startNode or endNode I will get extra nodes that are actually not connected to each other.

This works perfectly fine in neo4j cypher but I don't know how to do startNode and endNode (Scalar functions) in c#.

Currently I have this:

 var data = client.Cypher.Match("(n1)")
            .Where((Node n1) => n1.Identifier == identifier)
            .OptionalMatch("p=(n1)-[:r1|r1*2"]-(n2)")
            .Unwind("relationships(p)", "rel")
            .ReturnDistinct((n1, rel, n2) => new
            {
                startNode = n1.As<Node<string>>(),
                endNode = n2.As<Node<string>>(),
                relationship = rel.As<RelationshipInstance<object>>()
            }).Results;

This is not doing the startNode and endNode functions and so I get the extra nodes-relationships that are actually not connected to each other

Any ideas on how to achieve startNode and endNode functions in c# neo4j client?

Answer 1

You need to use the Return.As parts of Neo4jClient, the below query matches your original Cypher (well, including the Optional you use in your C# version):

var query = client.Cypher.Match("(n1)")
           .Where((Node n1) => n1.Identifier == identifier)
           .OptionalMatch("p=(n1)-[:r1|r2*..2]->(n2)")
           .Unwind("relationships(p)", "rel")
           .ReturnDistinct((n1, rel, n2) => new
           {
               startNode = Return.As<Node<string>>("startNode(rel)"),
               endNode = Return.As<Node<string>>("endNode(rel)"),
               relationship = Return.As<string>("type(rel)")
           });

The Return.As allows you to call the functions you want to.