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    Basic Neo4j Code Examples 2008-05-08

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    mmyoung2
    This document contains code snippets demonstrating how to build and traverse a graph database using Neo4j. The code first shows how to create nodes and relationships to build a social network graph of "The Matrix" characters. It then demonstrates traversing the graph to find "Mr. Anderson's friends." Finally, the domain is evolved to find friends who are "in love" by customizing the traversal logic.

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    Attribution Non-Commercial (BY-NC)
    Download as PDF, TXT or read online from Scribd

    Basic Neo4j Code Examples 2008-05-08

    Uploaded by

    mmyoung2
    37 views16 pages
    This document contains code snippets demonstrating how to build and traverse a graph database using Neo4j. The code first shows how to create nodes and relationships to build a social network graph of "The Matrix" characters. It then demonstrates traversing the graph to find "Mr. Anderson's friends." Finally, the domain is evolved to find friends who are "in love" by customizing the traversal logic.

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    This document contains code snippets demonstrating how to build and traverse a graph database using Neo4j. The code first shows how to create nodes and relationships to build a social network graph of "The Matrix" characters. It then demonstrates traversing the graph to find "Mr. Anderson's friends." Finally, the domain is evolved to find friends who are "in love" by customizing the traversal logic.

    Copyright:

    Attribution Non-Commercial (BY-NC)
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    37 views16 pages

    Basic Neo4j Code Examples 2008-05-08

    Uploaded by

    mmyoung2
    This document contains code snippets demonstrating how to build and traverse a graph database using Neo4j. The code first shows how to create nodes and relationships to build a social network graph of "The Matrix" characters. It then demonstrates traversing the graph to find "Mr. Anderson's friends." Finally, the domain is evolved to find friends who are "in love" by customizing the traversal logic.

    Copyright:

    Attribution Non-Commercial (BY-NC)
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 16

    some code snippets

    Neo

    Emil Eifrem

    2008-05-08, API v1.0-rc1-SNAPSHOT

    A few brief Neo4j code slides


    The following is a few slides from a live presentation hopefully the code is selfexplanatory But if it isnt, please join the discussion on the mailing list @ http://lists.neo4j.org First: how to create a node space Second: how to traverse that node space

    Example: The Matrix social graph


    name = The Architect name = Morpheus rank = Captain occupation = Total badass disclosure = public name = Thomas Anderson age = 29

    42

    KNOWS

    7
    S KNOW

    KNOWS

    KN O WS

    CODED_BY

    KN

    OW

    name = Cypher last name = Reagan disclosure = secret age = 6 months

    13
    name = Agent Smith version = 1.0b language = C++

    age = 3 days

    2
    name = Trinity

    Code (1): Building a node space


    NeoService neo = ... // Get factory // Create Thomas 'Neo' Anderson Node mrAnderson = neo.createNode(); mrAnderson.setProperty( "name", "Thomas Anderson" ); mrAnderson.setProperty( "age", 29 ); // Create Morpheus Node morpheus = neo.createNode(); morpheus.setProperty( "name", "Morpheus" ); morpheus.setProperty( "rank", "Captain" ); morpheus.setProperty( "occupation", "Total bad ass" ); // Create a relationship representing that they know each other mrAnderson.createRelationshipTo( morpheus, RelTypes.KNOWS ); // ...create Trinity, Cypher, Agent Smith, Architect similarly

    Code (1): Building a node space


    NeoService neo = ... // Get factory Transaction tx = neo.beginTransaction(); // Create Thomas 'Neo' Anderson Node mrAnderson = neo.createNode(); mrAnderson.setProperty( "name", "Thomas Anderson" ); mrAnderson.setProperty( "age", 29 ); // Create Morpheus Node morpheus = neo.createNode(); morpheus.setProperty( "name", "Morpheus" ); morpheus.setProperty( "rank", "Captain" ); morpheus.setProperty( "occupation", "Total bad ass" ); // Create a relationship representing that they know each other mrAnderson.createRelationshipTo( morpheus, RelTypes.KNOWS ); // ...create Trinity, Cypher, Agent Smith, Architect similarly tx.commit(); // Pseudo code, obviously wrap it in try-finally

    Traversal: Find Mr Andersons friends


    name = The Architect name = Morpheus rank = Captain occupation = Total badass disclosure = public name = Thomas Anderson age = 29

    42

    KNOWS

    7
    S KNOW

    KNOWS

    KN O WS

    CODED_BY

    KN

    OW

    name = Cypher last name = Reagan disclosure = secret age = 6 months

    13
    name = Agent Smith version = 1.0b language = C++

    age = 3 days

    2
    name = Trinity

    What do we want to do?


    We want to find all Mr Andersons transitive friends So conceptually, we want to traverse, starting from the Mr Anderson node... ... breadth first (closest friends first) ... until the end of the network (ALL friends) ... returning all nodes we visit, except the first one (only Mr Andersons friends, not Mr Anderson himself) ... but only traverse relationships of the KNOWS type in the OUTGOING direction

    Code (2): Traversing a node space


    // Instantiate a traverser that returns Mr Anderson's friends Traverser friendsTraverser = mrAnderson.traverse( Traverser.Order.BREADTH_FIRST, StopEvaluator.END_OF_NETWORK, ReturnableEvaluator.ALL_BUT_START_NODE, RelTypes.KNOWS, Direction.OUTGOING ); // Traverse the node space and print out the result System.out.println( "Mr Anderson's friends:" ); for ( Node friend : friendsTraverser ) { System.out.printf( "At depth %d => %s%n", friendsTraverser.currentPosition().getDepth(), friend.getProperty( "name" ) ); }

    name = The Architect name = Morpheus rank = Captain occupation = Total badass disclosure = public

    name = Thomas Anderson age = 29

    42

    KNOWS

    7
    KNOW S

    KNOWS

    KN O WS

    CODED_BY

    KN

    OW

    name = Cypher last name = Reagan disclosure = secret age = 6 months

    13
    name = Agent Smith version = 1.0b language = C++

    age = 3 days

    2
    name = Trinity

    $ bin/start-neo-example Mr Anderson's friends: At At At At $ depth depth depth depth 1 1 2 3 => => => => Morpheus Trinity Cypher Agent Smith

    friendsTraverser = mrAnderson.traverse( Traverser.Order.BREADTH_FIRST, StopEvaluator.END_OF_NETWORK, ReturnableEvaluator.ALL_BUT_START_NODE, RelTypes.KNOWS, Direction.OUTGOING );

    Evolving the domain: Friends in love?


    name = The Architect name = Morpheus rank = Captain occupation = Total badass disclosure = public name = Thomas Anderson age = 29

    42

    KNOWS

    7
    S KNOW

    KNOWS

    KN O WS

    CODED_BY

    KN LO

    OW

    name = Cypher last name = Reagan disclosure = secret age = 6 months

    13
    name = Agent Smith version = 1.0b language = C++

    VE

    2
    name = Trinity

    What do we want to do?


    Weve now extended the domain with completely new functionality Note how we dont have any predefined schemas we could even create the new reltype dynamically without restarting our app Conceptually, we want to find everyone amongst Mr Andersons friends who has a crush on someone So we still want to traverse all Mr Andersons friends (like last time) But this time we only want to return the nodes that has an OUTGOING relationship of the LOVES type

    Code (3a): Custom traverser


    // Create a traverser that returns all friends in love Traverser loveTraverser = mrAnderson.traverse( Traverser.Order.BREADTH_FIRST, StopEvaluator.END_OF_NETWORK, new ReturnableEvaluator() { public boolean isReturnableNode( TraversalPosition pos ) { return pos.currentNode().hasRelationship( RelTypes.LOVES, Direction.OUTGOING ); } }, RelTypes.KNOWS, Direction.OUTGOING );

    Code (3a): Custom traverser


    // Traverse the node space and print out the result System.out.println( "Whos in love?" ); for ( Node person : loveTraverser ) { System.out.printf( "At depth %d => %s%n", loveTraverser.currentPosition().getDepth(), person.getProperty( "name" ) ); }

    name = The Architect name = Morpheus rank = Captain occupation = Total badass disclosure = public

    name = Thomas Anderson age = 29

    42

    1
    S LO VE

    KNOW S
    KN

    7
    KNOW S

    KNOW S

    K NO W S

    CODED_BY

    OW

    name = Cypher last name = Reagan disclosure = secret age = 6 months

    13
    name = Agent Smith version = 1.0b language = C++

    2
    name = Trinity

    new ReturnableEvaluator() { public boolean isReturnableNode( TraversalPosition pos) { return pos.currentNode(). hasRelationship( RelTypes.LOVES, Direction.OUTGOING ); } },

    $ bin/start-neo-example Whos in love? At depth 1 => Trinity $

    Summary
    API details http://api.neo4j.org Feedback http://lists.neo4j.org Download http://neo4j.org/download Business http://neotechnology.com

    www.neo4j.org

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