Neo4j::Bolt - query Neo4j using Bolt protocol


 use Neo4j::Bolt;
 $cxn = Neo4j::Bolt->connect("bolt://localhost:7687");
 $stream = $cxn->run_query(
   "MATCH (a) RETURN head(labels(a)) as lbl, count(a) as ct",
   {} # parameter hash required
 @names = $stream->field_names;
 while ( my @row = $stream->fetch_next ) {
   print "For label '$row[0]' there are $row[1] nodes.\n";
 $stream = $cxn->run_query(
   "MATCH (a) RETURN labels(a) as lbls, count(a) as ct",
   {} # parameter hash required
 while ( my @row = $stream->fetch_next ) {
   print "For label set [".join(',',@{$row[0]})."] there are $row[1] nodes.\n";


Neo4j::Bolt is a Perl wrapper around Chris Leishmann's excellent libneo4j-client library implementing the Neo4j Bolt network protocol. It uses Ingy's Inline::C to do all the hard XS work.

Return Types

Neo4j::Bolt::ResultStream returns rows resulting from queries made via a Neo4j::Bolt::Cxn. These rows are simple arrays of scalars and/or references. These represent Neo4j types according to the following:

 Neo4j type       Perl representation
 ----- ----       ---- --------------
 Null             undef
 Bool             JSON::PP::Boolean (acts like 0 or 1)
 Int              scalar
 Float            scalar
 String           scalar
 Bytes            scalar
 List             arrayref
 Map              hashref
 Node             hashref  (Neo4j::Bolt::Node)
 Relationship     hashref  (Neo4j::Bolt::Relationship)
 Path             arrayref (Neo4j::Bolt::Path)

Nodes, Relationships and Paths are represented in the following formats:

 # Node:
 bless {
   id => $node_id,  labels => [$label1, $label2, ...],
   properties => {prop1 => $value1, prop2 => $value2, ...}
 }, 'Neo4j::Bolt::Node'

 # Relationship:
 bless {
   id => $reln_id,  type => $reln_type,
   start => $start_node_id,  end => $end_node_id,
   properties => {prop1 => $value1, prop2 => $value2, ...}
 }, 'Neo4j::Bolt::Relationship'

 # Path:
 bless [
   $node1, $reln12, $node2, $reln23, $node3, ...
 ], 'Neo4j::Bolt::Path'


connect($url), connect_tls($url,$tls_hash)

Class method, connect to Neo4j server. The URL scheme must be 'bolt', as in

  $url = 'bolt://localhost:7687';

Returns object of type Neo4j::Bolt::Cxn, which accepts Cypher queries and returns a Neo4j::Bolt::ResultStream.

To connect by SSL/TLS, use connect_tls, with a hashref with keys as follows

  ca_dir => <path/to/dir/of/CAs
  ca_file => <path/to/file/of/CAs
  pk_file => <path/to/private/
  pk_pass => <private/ passphrase>


  $cxn = Neo4j::Bolt->connect_tls('bolt://', { ca_cert => '/etc/ssl/cert.pem' });

When neither ca_dir nor ca_file are specified, an attempt will be made to use the default trust store instead. This requires IO::Socket::SSL or Mozilla::CA to be installed.


When $LEVEL is set to one of the strings ERROR WARN INFO DEBUG or TRACE, libneo4j-client native logger will emit log messages at or above the given level, on STDERR.

Set to NONE to turn off completely (the default).


Neo4j::Bolt::Cxn, Neo4j::Bolt::ResultStream.


 Mark A. Jensen
 majensen -at- cpan -dot- org


Arne Johannessen (@johannessen)


This software is Copyright (c) 2019-2021 by Mark A. Jensen.

This is free software, licensed under:

  The Apache License, Version 2.0, January 2004