Awesome Procedures for Neo4j 3.x

Documentation (WIP).

Introduction

Neo4j 3.0 introduced the concept of user defined procedures. Those are custom implementations of certain functionality, that can’t be (easily) expressed in Cypher itself. Those procedures are implemented in Java and can be easily deployed into your Neo4j instance, and then be called from Cypher directly.

The APOC library consists of many (about 300) procedures to help with many different tasks in areas like data integration, graph algorithms or data conversion.

License

Apache License 2.0

"APOC" Name history

Apoc was the technician and driver on board of the Nebuchadnezzar in the Matrix movie. He was killed by Cypher.

APOC was also the first bundled A Package Of Components for Neo4j in 2009.

APOC also stands for "Awesome Procedures On Cypher"

Download latest release

Go to http://github.com/neo4j-contrib/neo4j-apoc-procedures/releases/latest to find the latest release and download the binary jar to place into your $NEO4J_HOME/plugins folder.

Build & install the current development branch from source

git clone http://github.com/neo4j-contrib/neo4j-apoc-procedures
cd neo4j-apoc-procedures
./gradlew shadow
cp build/libs/apoc-<version>-SNAPSHOT-all.jar $NEO4J_HOME/plugins/
$NEO4J_HOME/bin/neo4j restart

A full build including running the tests can be run by ./gradlew build.

Calling Procedures within Cypher

Procedures can be called stand-alone with CALL procedure.name();

But you can also integrate them into your Cypher statements which makes them so much more powerful.

Load JSON example

WITH 'https://raw.githubusercontent.com/neo4j-contrib/neo4j-apoc-procedures/master/src/test/resources/person.json' AS url

CALL apoc.load.json(url) YIELD value as person

MERGE (p:Person {name:person.name})
   ON CREATE SET p.age = person.age, p.children = size(person.children)

Procedure Signatures

To call procedures correctly, you need to know their parameter names, types and positions. And for YIELDing their results the output column name and type.

You can see the procedures signature in the output of CALL dbms.procedures()

CALL dbms.procedures() YIELD name, signature
WITH * WHERE name STARTS WITH 'apoc.algo.dijkstra'
RETURN name, signature

The signature is always name : : TYPE, so in this case:

apoc.algo.dijkstra
 (startNode :: NODE?, endNode :: NODE?,
   relationshipTypesAndDirections :: STRING?, weightPropertyName :: STRING?)
:: (path :: PATH?, weight :: FLOAT?)

Parameters:

Name	Type
Procedure Parameters
startNode	Node
endNode	Node
relationshipTypesAndDirections	String
weightPropertyName	String
Output Return Columns
path	Path
weight	Float

Included Procedures Overview

All included procedures are listed in the overview in the documentation and detailed in subsequent sections.

Built in Help

call apoc.help('search')

lists name, description-text and if the procedure performs writes (descriptions are WIP), search string is checked against beginning (package) or end (name) of procedure

helpful

CALL apoc.help("apoc") YIELD name, text
WITH * WHERE text IS null
RETURN name AS undocumented

Builtin Package and Procedure count

To find the procedure count with the package in Neo4j:

Cypher for getting count of procedure in a package

CALL dbms.procedures() YIELD name
RETURN head(split(name,".")) as package, count(*), collect(name) as procedures;

Version Compatibility Matrix

Since APOC relies in some places on Neo4j’s internal APIs you need to use the right APOC version for your Neo4j installaton.

Any version to be released after 1.1.0 will use a different, consistent versioning scheme: <neo4j-version>.<apoc> version. The trailing <apoc> part of the version number will be incremented with every apoc release.

apoc version	neo4j version
3.0.4.1	3.0.4
1.1.0	3.0.0 - 3.0.3
1.0.0	3.0.0 - 3.0.3

Feedback

Please provide feedback and report bugs as GitHub issues or join the neo4j-users Slack and ask on the #apoc channel. You might also ask on StackOverflow, please tag your question there with neo4j and apoc.