NeoEloquent

Neo4j Graph Eloquent Driver for Laravel 5.

Quick Reference

• Installation
• Configuration
• Models
• Relationships
• Edges
• Migration
• Schema
• Aggregates
• Only in Neo
• Things To Avoid

Installation

Run composer require vinelab/neoeloquent

Or add the package to your composer.json and run composer update.

{
    "require": {
        "vinelab/neoeloquent": "1.8.*"
    }
}

Add the service provider in app/config/app.php:

'Vinelab\NeoEloquent\NeoEloquentServiceProvider',

The service provider will register all the required classes for this package and will also alias the Model class to NeoEloquent so you can simply extend NeoEloquent in your models.

Configuration

Connection

in app/config/database.php or in case of an environment-based configuration app/config/[env]/database.php make neo4j your default connection:

'default' => 'neo4j',

Add the connection defaults:

'connections' => [
    'neo4j' => [
        'driver' => 'neo4j',
        'host'   => 'localhost',
        'port'   => '7474',
        'username' => null,
        'password' => null
    ]
]

Migration Setup

If you're willing to have migrations:

• create the folder app/database/labels
• modify composer.json and add app/database/labels to the classmap array
• run composer dump-autoload

Documentation

Models

• Node Labels
• Soft Deleting

class User extends NeoEloquent {}

As simple as it is, NeoEloquent will generate the default node label from the class name, in this case it will be :User. Read about node labels here

Namespaced Models

When you use namespaces with your models the label will consider the full namespace.

namespace Vinelab\Cms;

class Admin extends NeoEloquent { }

The generated label from that relationship will be VinelabCmsAdmin, this is necessary to make sure that labels do not clash in cases where we introduce another Admin instance like Vinelab\Blog\Admin then things gets messy with :Admin in the database.

Custom Node Labels

You may specify the label(s) you wish to be used instead of the default generated, they are also case sensitive so they will be stored as put here.

class User extends NeoEloquent {

    protected $label = 'User'; // or array('User', 'Fan')

    protected $fillable = ['name', 'email'];
}

$user = User::create(['name' => 'Some Name', 'email' => '[email protected]']);

NeoEloquent has a fallback support for the $table variable that will be used if found and there was no $label defined on the model.

class User extends NeoEloquent {

    protected $table = 'User';

}

Do not worry about the labels formatting, You may specify them as array('Label1', 'Label2') or separate them by a column : and prepending them with a : is optional.

Soft Deleting

To enable soft deleting you'll need to use Vinelab\NeoEloquent\Eloquent\SoftDeletingTrait instead of Illuminate\Database\Eloquent\SoftDeletingTrait and just like Eloquent you'll need the $dates in your models as follows:

use Vinelab\NeoEloquent\Eloquent\SoftDeletingTrait;

class User extends NeoEloquent {

    use SoftDeletingTrait;

    protected $dates = ['deleted_at'];

}

Relationships

• One-To-One
• One-To-Many
• Many-To-Many
• Polymorphic

Let's go through some examples of relationships between Nodes.

One-To-One

class User extends NeoEloquent {

    public function phone()
    {
        return $this->hasOne('Phone');
    }

This represents an OUTGOING relationship direction from the :User node to a :Phone.

Saving

$phone = new Phone(['code' => 961, 'number' => '98765432'])
$relation = $user->phone()->save($phone);

The Cypher performed by this statement will be as follows:

MATCH (user:`User`)
WHERE id(user) = 1
CREATE (user)-[:PHONE]->(phone:`Phone` {code: 961, number: '98765432', created_at: 7543788, updated_at: 7543788})
RETURN phone;

Defining The Inverse Of This Relation

class Phone extends NeoEloquent {

    public function user()
    {
        return $this->belongsTo('User');
    }
}

This represents an INCOMING relationship direction from the :User node to this :Phone node.

Associating Models

Due to the fact that we do not deal with foreign keys, in our case it is much more than just setting the foreign key attribute on the parent model. In Neo4j (and Graph in general) a relationship is an entity itself that can also have attributes of its own, hence the introduction of Edges

Note: Associated models does not persist relations automatically when calling associate().

$account = Account::find(1986);

// $relation will be Vinelab\NeoEloquent\Eloquent\Edges\EdgeIn
$relation = $user->account()->associate($account);

// Save the relation
$relation->save();

The Cypher performed by this statement will be as follows:

MATCH (account:`Account`), (user:`User`)
WHERE id(account) = 1986 AND id(user) = 9862
MERGE (account)<-[rel_user_account:ACCOUNT]-(user)
RETURN rel_user_account;

One-To-Many

class User extends NeoEloquent {

    public function posts()
    {
        return $this->hasMany('Post', 'POSTED');
    }
}

This represents an OUTGOING relationship direction from the :User node to the :Post node.

$user = User::find(1);
$post = new Post(['title' => 'The Title', 'body' => 'Hot Body']);
$user->posts()->save($post);

Similar to One-To-One relationships the returned value from a save() statement is an Edge[In|Out]

The Cypher performed by this statement will be as follows:

MATCH (user:`User`)
WHERE id(user) = 1
CREATE (user)-[rel_user_post:POSTED]->(post:`Post` {title: 'The Title', body: 'Hot Body', created_at: '15-05-2014', updated_at: '15-05-2014'})
RETURN rel_user_post;

Defining The Inverse Of This Relation

class Post extends NeoEloquent {

    public function author()
    {
        return $this->belongsTo('User', 'POSTED');
    }
}

This represents an INCOMING relationship direction from the :User node to this :Post node.

Many-To-Many

class User extends NeoEloquent {

    public function followers()
    {
        return $this->belongsToMany('User', 'FOLLOWS');
    }
}

This represents an INCOMING relationship between a :User node and another :User.

$jd = User::find(1012);
$mc = User::find(1013);

$jd follows $mc:

$jd->followers()->save($mc);

Or using the attach() method:

$jd->followers()->attach($mc);
// Or..
$jd->followers()->attach(1013); // 1013 being the id of $mc ($mc->getKey())

The Cypher performed by this statement will be as follows:

MATCH (user:`User`), (followers:`User`)
WHERE id(user) = 1012 AND id(followers) = 1013
CREATE (followers)-[:FOLLOWS]->(user)
RETURN rel_follows;

$mc follows $jd back:

$mc->followers()->save($jd);

The Cypher performed by this statement will be as follows:

MATCH (user:`User`), (followers:`User`)
WHERE id(user) = 1013 AND id(followers) = 1012
CREATE (user)-[rel_user_followers:FOLLOWS]->(followers)
RETURN rel_follows;

get the followers of $jd

$followers = $jd->followers;

The Cypher performed by this statement will be as follows:

MATCH (user:`User`), (followers:`User`), (user)-[rel_user_followers:FOLLOWS]-(followers)
WHERE id(user) = 1012
RETURN rel_follows;

Dynamic Properties

class Phone extends NeoEloquent {

    public function user()
    {
        return $this->belongsTo('User');
    }

}

$phone = Phone::find(1006);
$user = $phone->user;
// or getting an attribute out of the related model
$name = $phone->user->name;

Polymorphic

The concept behind Polymorphic relations is purely relational to the bone but when it comes to graph we are representing it as a HyperEdge.

Hyper edges involves three models, the parent model, hyper model and related model represented in the following figure:

Similarly in code this will be represented by three models User Comment and Post where a User with id 1 posts a Post and a User with id 6 COMMENTED a Comment ON that Post as follows:

class User extends NeoEloquent {

    public function comments($morph = null)
    {
        return $this->hyperMorph($morph, 'Comment', 'COMMENTED', 'ON');
    }

}

In order to keep things simple but still involving the three models we will have to pass the $morph which is any commentable model, in our case it's either a Video or a Post model.

Note: Make sure to have it defaulting to null so that we can Dynamicly or Eager load with $user->comments later on.

Creating a Comment with the create() method.

$user = User::find(6);
$post = Post::find(2);

$user->comments($post)->create(['text' => 'Totally agree!', 'likes' => 0, 'abuse' => 0]);

As usual we will have returned an Edge, but this time it's not directed it is an instance of HyperEdge, read more about HyperEdges here.

Or you may save a Comment instance:

$comment = new Comment(['text' => 'Magnificent', 'likes' => 0, 'abuse' => 0]);

$user->comments($post)->save($comment);

Also all the functionalities found in a BelongsToMany relationship are supported like attaching models by Ids:

$user->comments($post)->attach([$id, $otherId]);

Or detaching models:

$user->comments($post)->detach($comment); // or $comment->id

Sync too:

$user->comments($post)->sync([$id, $otherId, $someId]);

Retrieving Polymorphic Relations

From our previous example we will use the Video model to retrieve their comments:

class Video extends NeoEloquent {

    public function comments()
    {
        return $this->morphMany('Comment', 'ON');
    }

}

Dynamicly Loading Morph Model

$video = Video::find(3);
$comments = $video->comments;

Eager Loading Morph Model

$video = Video::with('comments')->find(3);
foreach ($video->comments as $comment)
{
    //
}

Retrieving The Inverse of a Polymorphic Relation

class Comment extends NeoEloquent {

    public function commentable()
    {
        return $this->morphTo();
    }

}

$postComment = Comment::find(7);
$post = $comment->commentable;

$videoComment = Comment::find(5);
$video = $comment->commentable;

// You can also eager load them
Comment::with('commentable')->get();

You may also specify the type of morph you would like returned:

class Comment extends NeoEloquent {

    public function post()
    {
        return $this->morphTo('Post', 'ON');
    }

    public function video()
    {
        return $this->morphTo('Video', 'ON');
    }

}

Polymorphic Relations In Short

To drill things down here's how our three models involved in a Polymorphic relationship connect:

class User extends NeoEloquent {

    public function comments($morph = null)
    {
        return $this->hyperMorph($morph, 'Comment', 'COMMENTED', 'ON');
    }

}

class Post extends NeoEloquent { // Video is the same as this one

    public function comments()
    {
        return $this->morphMany('Comment', 'ON');
    }

}

class Comment extends NeoEloquent {

    public function commentable()
    {
        return $this->morphTo();
    }

}

Eager Loading

class Book extends NeoEloquent {

    public function author()
    {
        return $this->belongsTo('Author');
    }
}

Loading authors with their books with the least performance overhead possible.

foreach (Book::with('author')->get() as $book)
{
    echo $book->author->name;
}

Only two Cypher queries will be run in the loop above:

MATCH (book:`Book`) RETURN *;

MATCH (book:`Book`), (book)<-[:WROTE]-(author:`Author`) WHERE id(book) IN [1, 2, 3, 4, 5, ...] RETURN book, author;

Edges

• EdgeIn
• EdgeOut
• HyperEdge
• Working with Edges
• Edge Attributes

Introduction

Due to the fact that relationships in Graph are much different than other database types so we will have to handle them accordingly. Relationships have directions that can vary between In and Out respectively towards the parent node.

Edges give you the ability to manipulate relationships properties the same way you do with models.

$edge = $location->associate($user);
$edge->last_visited = 'today';
$edge->save(); // true

EdgeIn

Represents an INCOMING direction relationship from the related model towards the parent model.

class Location extends NeoEloquent {

    public function user()
    {
        return $this->belongsTo('User', 'LOCATED_AT');
    }

}

To associate a User to a Location:

$location = Location::find(1922);
$user = User::find(3876);
$relation = $location->associate($user);

which in Cypher land will map to (:Location)<-[:LOCATED_AT]-(:User) and $relation being an instance of EdgeIn representing an incoming relationship towards the parent.

And you can still access the models from the edge:

$relation = $location->associate($user);
$location = $relation->parent();
$user = $relation->related();

EdgeOut

Represents an OUTGOING direction relationship from the parent model to the related model.

class User extends NeoEloquent {

    public function posts()
    {
        return $this->hasMany('Post', 'POSTED');
    }

}

To save an outgoing edge from :User to :Post it goes like:

$post = new Post(['...']);
$posted = $user->posts()->save($post);

Which in Cypher would be (:User)-[:POSTED]->(:Post) and $posted being the EdgeOut instance.

And fetch the related models:

$edge = $user->posts()->save($post);
$user = $edge->parent();
$post = $edge->related();

HyperEdge

This edge comes as a result of a Polymorphic Relation representing an edge involving two other edges left and right that can be accessed through the left() and right() methods.

This edge is treated a bit different than the others since it is not a direct relationship between two models which means it has no specific direction.

$edge = $user->comments($post)->attach($comment);
// Access the left and right edges
$left = $edge->left();
$user = $left->parent();
$comment = $left->related();

$right = $edge->right();
$comment = $right->parent();
$post = $right->related();

Working With Edges

As stated earlier Edges are entities to Graph unlike SQL where they are a matter of a foreign key having the value of the parent model as an attribute on the belonging model or in Documents where they are either embeds or ids as references. So we developed them to be light models which means you can work with them as if you were working with an Eloquent instance - to a certain extent, except HyperEdges.

// Create a new relationship
$relation = $location->associate($user); // Vinelab\NeoEloquent\Eloquent\Edges\EdgeIn

// Save the relationship to the database
$relation->save(); // true

In the case of a HyperEdge you can access all three models as follows:

$edge    = $user->comments($post)->save($comment);
$user    = $edge->parent();
$comment = $edge->hyper();
$post    = $edge->related();

Edge Attributes

By default, edges will have the timestamps created_at and updated_at automatically set and updated only if timestamps are enabled by setting $timestamps to true on the parent model.

$located_at = $location->associate($user);
$located_at->since = 1966;
$located_at->present = true;
$located_at->save();

// $created_at and $updated_at are Carbon\Carbon instances
$created_at = $located_at->created_at;
$updated_at = $located_at->updated_at;

Retrieve an Edge from a Relation

The same way an association will create an EdgeIn relationship we can retrieve the edge between two models by calling the edge($model) method on the belongsTo relationship.

$location = Location::find(1892);
$edge = $location->user()->edge();

You may also specify the model at the other side of the edge.

Note: By default NeoEloquent will try to pefrorm the $location->user internally to figure out the related side of the edge based on the relation function name, in this case it's user().

$location = Location::find(1892);
$edge = $location->user()->edge($location->user);

Only in Neo

• CreateWith

Here you will find NeoEloquent-specific methods and implementations that with the wonderful Eloquent methods would make working with Graph and Neo4j a blast!

CreateWith

• Creating Relations
• Attaching Relations

This method will "kind of" fill the gap between relational and document databases, it allows the creation of multiple related models with one database hit.

Creating New Records and Relations

Here's an example of creating a post with attached photos and videos:

class Post extends NeoEloquent {

    public function photos()
    {
        return $this->hasMany('Photo', 'PHOTO');
    }

    public function videos()
    {
        return $this->hasMany('Video', 'VIDEO');
    }
}

Post::createWith(['title' => 'the title', 'body' => 'the body'], [
    'photos' => [
        [
            'url'      => 'http://url',
            'caption'  => '...',
            'metadata' => '...'
        ],
        [
            'url' => 'http://other.url',
            'caption' => 'the bay',
            'metadata' => '...'
        ]
    ],

    'videos' => [
        'title' => 'Boats passing us by',
        'description' => '...'
    ]
]);

The keys photos and videos must be the same as the relation method names in the Post model.

The Cypher query performed by the example above is:

CREATE (post:`Post` {title: 'the title', body: 'the body'}),
(post)-[:PHOTO]->(:`Photo` {url: 'http://url', caption: '...', metadata: '...'}),
(post)-[:PHOTO]->(:`Photo` {url: 'http://other', caption: 'the bay', metadata: '...'}),
(post)-[:VIDEO]->(:`Video` {title: 'Boats passing us by', description: '...'});

We will get the nodes created with their relations as such:

You may also mix models and attributes as relation values but it is not necessary since NeoEloquent will pass the provided attributes through the $fillable filter pipeline:

$videos = new Video(['title' => 'foo', 'description' => 'bar']);
Post::createWith($info, compact('videos'));

You may also use a single array of attributes as such:

class User extends NeoEloquent {

    public function account()
    {
        return $this->hasOne('Account');
    }
}

User::createWith(['name' => 'foo'], ['account' => ['guid' => 'bar', 'email' => '[email protected]']]);

Attaching Existing Records as Relations

createWith is intelligent enough to know the difference when you pass an existing model, a model Id or new records that you need to create which allows mixing new records with existing ones.

class Post extends NeoEloquent {

    public function tags()
    {
        return $this->hasMany('Tag', 'TAG');
    }
}

$tag1 = Tag::create(['title' => 'php']);
$tag2 = Tag::create(['title' => 'dev']);

$post = Post::createWith(['title' => 'foo', 'body' => 'bar'], ['tags' => [$tag1, $tag2]]);

And we will get the Post related to the existing Tag nodes.

Or using the id of the model:

Post::createWith(['title' => 'foo', 'body' => 'bar'], ['tags' => 1, 'privacy' => 2]);

The Cypher for the query that attaches records would be:

CREATE (post:`Post` {title: 'foo', 'body' => 'bar'})
WITH post
MATCH (tag:`Tag`)
WHERE id(tag) IN [1, 2]
CREATE (post)-[:TAG]->(tag);

Migration

For migrations to work please perform the following:

• create the folder app/database/labels
• modify composer.json and add app/database/labels to the classmap array

Since Neo4j is a schema-less database you don't need to predefine types of properties for labels. However you will be able to perform Indexing and Constraints using NeoEloquent's pain-less Schema.

Commands

NeoEloquent introduces new commands under the neo4j namespace so you can still use Eloquent's migration commands side-by-side.

Migration commands are the same as those of Eloquent, in the form of neo4j:migrate[:command]

neo4j:make:migration                 Create a new migration file
neo4j:migrate                        Run the database migrations
neo4j:migrate:reset                  Rollback all database migrations
neo4j:migrate:refresh                Reset and re-run all migrations
neo4j:migrate:rollback               Rollback the last database migration

Creating Migrations

Like in Laravel you can create a new migration by using the make command with Artisan:

php artisan neo4j:migrate:make create_user_label

Label migrations will be placed in app/database/labels

You can add additional options to commands like:

php artisan neo4j:migrate:make foo --path=app/labels
php artisan neo4j:migrate:make create_user_label --create=User
php artisan neo4j:migrate:make create_user_label --label=User

Running Migrations

Run All Outstanding Migrations

php artisan neo4j:migrate

Run All Outstanding Migrations For A Path

php artisan neo4j:migrate --path=app/foo/labels

Run All Outstanding Migrations For A Package

php artisan neo4j:migrate --package=vendor/package

Note: If you receive a "class not found" error when running migrations, try running the composer dump-autoload command.

Forcing Migrations In Production

To force-run migrations on a production database you can use:

php artisan neo4j:migrate --force

Rolling Back Migrations

Rollback The Last Migration Operation

php artisan neo4j:migrate:rollback

Rollback all migrations

php artisan neo4j:migrate:reset

Rollback all migrations and run them all again

php artisan neo4j:migrate:refresh

php artisan neo4j:migrate:refresh --seed

Schema

NeoEloquent will alias the Neo4jSchema facade automatically for you to be used in manipulating labels.

Neo4jSchema::label('User', function(Blueprint $label)
{
    $label->unique('uuid');
});

If you decide to write Migration classes manually (not using the generator) make sure to have these use statements in place:

• use Vinelab\NeoEloquent\Schema\Blueprint;
• use Vinelab\NeoEloquent\Migrations\Migration;

Currently Neo4j supports UNIQUE constraint and INDEX on properties. You can read more about them at

http://docs.neo4j.org/chunked/stable/graphdb-neo4j-schema.html

Schema Methods

Droping Labels

Neo4jSchema::drop('User');
Neo4jSchema::dropIfExists('User');

Renaming Labels

Neo4jSchema::renameLabel($from, $to);

Checking Label's Existence

if (Neo4jSchema::hasLabel('User')) {

} else {

}

Checking Relation's Existence

if (Neo4jSchema::hasRelation('FRIEND_OF')) {

} else {

}

You can read more about migrations and schema on:

http://laravel.com/docs/schema

http://laravel.com/docs/migrations

Aggregates

In addition to the Eloquent builder aggregates, NeoEloquent also has support for Neo4j specific aggregates like percentile and standard deviation, keeping the same function names for convenience. Check the docs for more.

table() represents the label of the model

$users = DB::table('User')->count();

$distinct = DB::table('User')->countDistinct('points');

$price = DB::table('Order')->max('price');

$price = DB::table('Order')->min('price');

$price = DB::table('Order')->avg('price');

$total = DB::table('User')->sum('votes');

$disc = DB::table('User')->percentileDisc('votes', 0.2);

$cont = DB::table('User')->percentileCont('votes', 0.8);

$deviation = DB::table('User')->stdev('sex');

$population = DB::table('User')->stdevp('sex');

$emails = DB::table('User')->collect('email');

Changelog

Check the Releases for details.

Avoid

Here are some constraints and Graph-specific gotchas, a list of features that are either not supported or not recommended.

JOINS 😖

• They make no sense for Graph, plus Graph hates them! Which makes them unsupported on purpose. If migrating from an SQL-based app they will be your boogie monster.

Pivot Tables in Many-To-Many Relationships

This is not supported, instead we will be using Edges to work with relationships between models.

Nested Arrays and Objects

• Due to the limitations imposed by the objects map types that can be stored in a single, you can never have nested arrays or objects in a single model, make sure it's flat. Example:

// Don't
User::create(['name' => 'Some Name', 'location' => ['lat' => 123, 'lng'=> -123 ] ]);

Check out the createWith() method on how you can achieve this in a Graph way.

Tests

• install a Neo4j instance and run it with the default configuration localhost:7474
• make sure the database graph is empty to avoid conflicts
• after running composer install there should be /vendor/bin/phpunit
• run ./vendor/bin/phpunit after making sure that the Neo4j instance is running

Tests marked as incomplete means they are either known issues or non-supported features, check included messages for more info.

Factories

You can use default Laravel factory() helper for NeoEloquent models too.

• define needed factories inside database/factories/(read more)[https://laravel.com/docs/5.6/database-testing#writing-factories];
• use factory() in the same style as default Laravel factory().