Cypher to Neo4JClient Distinct Collect

Question

I am trying to get a path from a base node to its root node as 1 row. The Cypher query looks like this:

start n = node:node_auto_index(Name = "user1") match path = (n-[r:IS_MEMBER_OF_GROUP*]->b) return last(collect(distinct path));

But when changing this over to the Neo4JClient syntax:

var k = clientConnection.Cypher
                .Start(new { n = "node:node_auto_index(Name = 'user1')" })
                .Match("path = (n-[r:IS_MEMBER_OF_GROUP*]->b)")
                .ReturnDistinct<Node<Principles>>("last(collect(path))").Results;

It gets an error:

{"Value cannot be null.\r\nParameter name: uriString"}

When continuing on from there:

 Neo4jClient encountered an exception while deserializing the response from the server. This is likely a bug in Neo4jClient.



Please open an issue at https://bitbucket.org/Readify/neo4jclient/issues/new



To get a reply, and track your issue, ensure you are logged in on BitBucket before submitting.



Include the full text of this exception, including this message, the stack trace, and all of the inner exception details.



Include the full type definition of Neo4jClient.Node`1[[IQS_Neo4j_TestGraph.Nodes.Principles, IQS Neo4j TestGraph, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].



Include this raw JSON, with any sensitive values replaced with non-sensitive equivalents:



{

  "columns" : [ "last(collect(path))" ],

  "data" : [ [ {

    "start" : "http://localhost:7474/db/data/node/3907",

    "nodes" : [ "http://localhost:7474/db/data/node/3907", "http://localhost:7474/db/data/node/3906", "http://localhost:7474/db/data/node/3905", "http://localhost:7474/db/data/node/3904" ],

    "length" : 3,

    "relationships" : [ "http://localhost:7474/db/data/relationship/4761", "http://localhost:7474/db/data/relationship/4762", "http://localhost:7474/db/data/relationship/4763" ],

    "end" : "http://localhost:7474/db/data/node/3904"

  } ] ]

}

How would one convert the cypher query to Neo4JClient query?

Answer 1

Well, the thing you are returning is a PathsResult not a Node<>, so if you change your query to be:

 var k = clientConnection.Cypher
            .Start(new { n = "node:node_auto_index(Name = 'user1')" })
            .Match("path = (n-[r:IS_MEMBER_OF_GROUP*]->b)")
            .ReturnDistinct<PathsResult>("last(collect(path))").Results; //<-- Change here

you will get results, this returns what I get from running your query against my db, if you specifically want the nodes this post: Getting PathsResults covers converting to actual nodes and relationships.

One other thing, (and this will help the query perform better as neo4j can cache the execution plans easier), is that you can change your start to make it use parameters by doing:

.Start(new { n = Node.ByIndexLookup("node_auto_index", "Name", "user1")})