Everyman Software Musings on software development, open source, PHP and current projects. 2011-11-05 Development
Setup for Neo4j and PHP: Part 2 This is Part 2 of a series on setting up a development environment for building
projects using the graph database Neo4j and PHP. In Part 1 of this series, we set up unit test and development
databases. In this part, we'll build a skeleton project that includes unit tests, and a minimalistic user interface.
All the files will live under a directory on our web server. In a real project, you'll probably want only the user
interface files under the web server directory and your testing and library files somewhere more protected. Also, I
won't be using any specific PHP framework. The principles in the code below should apply equally to any framework you
decide to use. Create the Project and Testing HarnessCreate a project in a directory on your web server. For this
project, mine is "/var/www/neo4play" on my local host. We'll also need our Neo4j client library. > cd
/var/www/neo4play > mkdir -p tests/unit > mkdir lib > cp ~/Downloads/neo4jphp.phar lib/ > echo "<?php phpinfo(); ?>"
> index.php Test the setup by browsing to http://localhost/neo4play. You should see the output of `phpinfo`. Now
we'll create a bootstrap file that we can include to do project-wide and environment specific setup. Call this file
"bootstrap.php" in the root project directory. <?php require_once(__DIR__.'/lib/neo4jphp.phar'); error_reporting(-1);
ini_set('display_errors', 1); if (!defined('APPLICATION_ENV')) { define('APPLICATION_ENV', 'development'); } $host =
'localhost'; $port = (APPLICATION_ENV == 'development') ? 7474 : 7475; $transport = new
Everyman\Neo4j\Transport($host, $port); $client = new Everyman\Neo4j\Client($transport); The main point of this file
at the moment is to differentiate between our development and testing environments, and set up our connection to the
correct database. We do this by attaching the database client to the correct port based on an application constant.
We'll use the bootstrap file to setup a different, unit testing specific bootstrap file. Create the following file as
"tests/bootstap-test.php": <?php define('APPLICATION_ENV', 'testing'); require_once(__DIR__.'/../bootstrap.php');
$transport->delete('/cleandb/secret-key'); The purpose of this file to to tell our application bootstrap that we are
in the "testing" environment. Then it cleans out the database so that our tests run from a known state. Make sure
"secret-key" in the `delete()` call is whatever you set in the Neo4j config file from Part 1. Tell PHPUnit to use our
test bootstrap with the following config file, called "tests/phpunit.xml": <phpunit colors="true"
bootstrap="./bootstrap-test.php"> <testsuite name="Neo4j Play Test Results"> <directory>./unit</directory>
</testsuite> </phpunit> And because we're following TDD, we'll create our first test file,
"tests/unit/ActorTest.php": <?php class ActorTest extends PHPUnit_Framework_TestCase { public function
testCreateActorAndRetrieveByName() { $actor = new Actor(); $actor->name = 'Test Guy '.rand(); Actor::save($actor);
$actorId = $actor->id; self::assertNotNull($actorId); $retrievedActor = Actor::getActorByName($actor->name);
self::assertInstanceOf('Actor', $retrievedActor); self::assertEquals($actor->id, $retrievedActor->id);
self::assertEquals($actor->name, $retrievedActor->name); } public function testActorDoesNotExist() { $retrievedActor
= Actor::getActorByName('Test Guy '.rand()); self::assertNull($retrievedActor); } } So we know we want a domain
object called "Actor" (apparently we're building some sort of movie application) and that Actors have names and ids.
We also know we want to be able to look up an Actor by their name. If we can't find the Actor by name, we should get
a `null` value back. Run the tests: > cd tests > phpunit Excellent, our tests failed! If you've been playing along,
they probably failed because the "Actor" class isn't defined. Our next step is to start creating our domain objects.
Defining the Application DomainSo far, we only have one domain object, and a test that asserts its behavior. In order
to make the test pass, we'll need to connect to the database, persist entities to it, and then query it for those
entities. For persisting our entities, we'll need a way to get the client connection in our "Actor" class and any
other domain object classes we define. To do this, we'll create an application registry/dependency-injection
container/pattern-buzzword-of-the-month class. Put the following in the file "lib/Neo4Play.php": <?php class Neo4Play
{ protected static $client = null; public static function client() { return self::$client; } public static function
setClient(Everyman\Neo4j\Client $client) { self::$client = $client; } } Now our domain objects will have access to
the client connection through `Neo4Play::client()` when we persist them to the database. It's time to define our
actor class, in the file "lib/Actor.php": <?php use Everyman\Neo4j\Node, Everyman\Neo4j\Index; class Actor { public
$id = null; public $name = ''; public static function save(Actor $actor) { } public static function
getActorByName($name) { } } Requiring our classes and setting up the client connection is part of the bootstrapping
process of the application, so we'll need to add some thing to "bootstrap.php": <?php
require_once(__DIR__.'/lib/neo4jphp.phar'); require_once(__DIR__.'/lib/Neo4Play.php');
require_once(__DIR__.'/lib/Actor.php'); // ** set up error reporting, environment and connection... **//
Neo4Play::setClient($client); We have a stub class for the domain object. The tests will still fail when we run them
again, but at least all the classes should be found correctly. Let's start with finding an Actor by name. With our
knowledge of graph databases, we know this will involve an index lookup, and that we will get a Node object in
return. If the lookup returns no result, we'll get a `null`. If we do get a Node back, we'll want to hold on to it,
for updating the Actor later. Modify the Actor class with the following contents: class Actor { // protected $node =
null; // public static function getActorByName($name) { $actorIndex = new Index(Neo4Play::client(), Index::TypeNode,
'actors'); $node = $actorIndex->findOne('name', $name); if (!$node) { return null; } $actor = new Actor(); $actor->id
= $node->getId(); $actor->name = $node->getProperty('name'); $actor->node = $node; return $actor; } } The main thing
we're trying to accomplish here is keeping our domain classes as Plain-Old PHP Objects, that don't require any
special class inheritance or interface, and that hide the underlying persistence layer from the outside world. The
tests still fail. We'll finish up our Actor class by saving the Actor to the database. class Actor { // public static
function save(Actor $actor) { if (!$actor->node) { $actor->node = new Node(Neo4Play::client()); }
$actor->node->setProperty('name', $actor->name); $actor->node->save(); $actor->id = $actor->node->getId();
$actorIndex = new Index(Neo4Play::client(), Index::TypeNode, 'actors'); $actorIndex->add($actor->node, 'name',
$actor->name); } // } Run the tests again. If you see all green, then everything is working properly. To double
check, browse to the testing instance webadmin panel http://localhost:7475/webadmin/#. You should see 2 nodes and 1
property (Why 2 nodes? Because there is a node 0 -- the reference node -- that is not deleted when the database is
cleaned out.) Build Something UsefulIt's time to start tacking on some user functionality to our application. Thanks
to our work on the unit tests, we can create actors in the database and find them again via an exact name match.
Let's expose that functionality. Change the contents of "index.php" to the following: <?php
require_once('bootstrap.php'); if (!empty($_POST['actorName'])) { $actor = new Actor(); $actor->name =
$_POST['actorName']; Actor::save($actor); } else if (!empty($_GET['actorName'])) { $actor =
Actor::getActorByName($_GET['actorName']); } ?> <form action="" method="POST"> Add Actor Name: <input type="text"
name="actorName" /> <input type="submit" value="Add" /> </form> <form action="" method="GET"> Find Actor Name: <input
type="text" name="actorName" /> <input type="submit" value="Search" /> </form> <?php if (!empty($actor)) : ?> Name:
<?php echo $actor->name; ?><br /> Id: <?php echo $actor->id; ?><br /> <?php elseif (!empty($_GET['actorName'])) : ?>
No actor found by the name of "<?php echo $_GET['actorName']; ?>"<br /> <?php endif; ?> Browse to your index file.
Mine is at http://localhost/neo4play/index.php. You should see the page you just created. Enter a name in the "Add
Actor Name" box and click the "Add" button. If everything went according to plan, you should see the actor name and
the id assigned to the actor by the database. Try finding that actor using the search box. Note the actor's id.
Browse to http://localhost:7474/webadmin/# and click the "Data browser" tab. Enter the actor id in the text box at
the top. The node you created when you added the actor should show up. The interesting thing is that our actual
application doesn't know anything about how the Actors are stored. Nothing in "index.php" references graphs or nodes
or indexes. This means that, in theory, we could swap out the persistence layer for a SQL databases later, or
MongoDB, or anything else, and nothing in our application would have to change. If we started with a SQL database, we
could easily transition to a graph database. Explore the Wonderful World of GraphsYour development environment is now
set up, and your application is bootstrapped. There's a lot more to add to this application, including creating
movies, and linking actors and movies together. Maybe you'll want to add a social aspect, with movie recommendations.
Graph databases are powerful tools that enable such functionality to be added easily. Go ahead and explore the rest
of the Neo4jPHP library (wiki and API). Also, be sure to checkout the Neo4j documentation, especially the sections
about the REST API, Cypher and Gremlin (two powerful graph querying and processing languages.) All the code for this
sample application is available as a gist: http://gist.github.com/1341833. Happy graphing! by Josh Adell on
11/05/2011 Email ThisBlogThis!Share to TwitterShare to Facebook Labels: everyman, graph, neo4j, php 5 comments:
Daniel3dFebruary 24, 2012 11:24 AMHi i get this error when i try to add some node whit the index.php"  Fatal error:
Uncaught exception 'Everyman\Neo4j\Exception' with message 'Unable to search index [500]: Headers: Array ( ) Body:
Array ( [error] => Couldn't resolve host 'xubuntu' [6] ) ' in
phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Command.php:116 Stack trace: #0
phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Command/SearchIndex.php(95):
Everyman\Neo4j\Command->throwException('Unable to searc...', 500, Array, Array) #1
phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Command.php(69):
Everyman\Neo4j\Command\SearchIndex->handleResult(500, Array, Array) #2
phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Client.php(571): Everyman\Neo4j\Command->execute() #3
phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Client.php(513):
Everyman\Neo4j\Client->runCommand(Object(Everyman\Neo4j\Command\SearchIndex)) #4
phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Index.php(77):
Everyman\Neo4j\Client->searchIndex(Object(Everyman\Neo4j\Index), 'name',
inphar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Command.php on line 116
"ReplyDeleteDaniel3dFebruary 24, 2012 11:29 AMSorry this one is when i try to save. another one is when i search
Please help .AND THANKS JOSH ADELL GREAT JOB."  Fatal error: Uncaught exception 'Everyman\Neo4j\Exception' with
message 'Unable to create node [500]: Headers: Array ( ) Body: Array ( [error] => Couldn't resolve host 'xubuntu' [6]
) ' in phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Command.php:116 Stack trace: #0
phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Command/CreateNode.php(68):
Everyman\Neo4j\Command->throwException('Unable to creat...', 500, Array, Array) #1
phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Command.php(69):
Everyman\Neo4j\Command\CreateNode->handleResult(500, Array, Array) #2
phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Client.php(571): Everyman\Neo4j\Command->execute() #3
phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Client.php(478):
Everyman\Neo4j\Client->runCommand(Object(Everyman\Neo4j\Command\CreateNode)) #4
phar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Node.php(94):
Everyman\Neo4j\Client->saveNode(Object(Everyman\Neo4j\Node)) #5 /var/www/neo4
inphar:///var/www/neo4play/lib/neo4jphp.phar/lib/Everyman/Neo4j/Command.php on line 116"ReplyDeleteJosh AdellFebruary
24, 2012 12:10 PMIf you are using the example scripts from the Gist, you will need to change the $host variable in
bootstrap.php to be 'localhost' or whatever the hostname of your Neo4j instance is.ReplyDeleteDaniel3dFebruary 29,
2012 4:49 PMThanks work...ReplyDeleteKarthikbaluJuly 21, 2012 3:21 PMWow ur awesomeReplyDeleteAdd commentLoad more...
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Decode JSON in Bash with PHP Codeworks '11 Raleigh Rundown ?  November (2) Development Setup for Neo4j and PHP: Part
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?  August (1) Getting Neo4jPHP working with CodeIgniter 2 ?  July (4) Performance of Graph vs. Relational Databases
TriPUG Meetup slides agile Adoption on a Non-Technical Team Neo4jPHP beta released ?  June (2) Path finding with
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