NAME

Neo4j::Bolt::ResultStream - Iterator on Neo4j Bolt query response

SYNOPSIS

use Neo4j::Bolt;
$cxn = Neo4j::Bolt->connect("bolt://localhost:7687");

$stream = $cxn->run_query(
  "MATCH (a) RETURN labels(a) as lbls, count(a) as ct"
);
while ( my @row = $stream->fetch_next ) {
  print "For label set [".join(',',@{$row[0]})."] there are $row[1] nodes.\n";
}
# check that the stream emptied cleanly...
unless ( $stream->success ) {
  print STDERR "Uh oh: ".($stream->client_errmsg || $stream->server_errmsg);
}

DESCRIPTION

Neo4j::Bolt::ResultStream objects are created by a successful query performed on a Neo4j::Bolt::Cxn. They are iterated to obtain the rows of the response as Perl arrays (not arrayrefs).

METHODS

fetch_next()

Obtain the next row of results as an array. Returns false when done.

update_counts()

If a write query is successful, returns a hashref containing the numbers of items created or removed in the query. The keys indicate the items, as follows:

nodes_created
nodes_deleted
relationships_created
relationships_deleted
properties_set
labels_added
labels_removed
indexes_added
indexes_removed
constraints_added
constraints_removed

If query is unsuccessful, or the stream is not completely fetched yet, returns undef (check "server_errmsg()").

field_names()

Obtain the column names of the response as an array (not arrayref).

nfields()

Obtain the number of fields in the response row as an integer.

success(), failure()

Use these to check whether fetch_next() succeeded. They indicate the current error state of the result stream. If

$stream->success == $stream->failure == -1

then the stream has been exhausted.

client_errnum()

client_errmsg()

server_errcode()

server_errmsg()

If $stream->success is false, these will indicate what happened.

If the error occurred within the libneo4j-client code, client_errnum() will provide the errno and client_errmsg() the associated error message. This is a probably a good time to file a bug report.

If the error occurred at the server, server_errcode() and server_errmsg() will contain information sent by the server. In particular, Cypher syntax errors will appear here.

result_count_()

available_after()

consumed_after()

These are performance numbers that the server provides after the stream has been fetched out. result_count_() is the number of rows returned, available_after() is the time in ms it took the server to provide the stream, and consumed_after() is the time it took the client (you) to pull them all.

LIMITATIONS

The results of Cypher EXPLAIN or PROFILE queries are currently unsupported. If you need to access such results, consider using Neo4j::Driver or the interactive Neo4j Browser instead of this module.

SEE ALSO

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

AUTHOR

Mark A. Jensen
CPAN: MAJENSEN
majensen -at- cpan -dot- org

LICENSE

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