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NeoEloquent

Neo4j Graph Eloquent Driver for Laravel.

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.

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

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:

Add the connection defaults:

Remember to update your ENV variables (.env) in case you're using them.

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

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.

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.

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

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:

Relationships

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

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

One-To-One

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

Saving

The Cypher performed by this statement will be as follows:

Defining The Inverse Of This Relation

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().

The Cypher performed by this statement will be as follows:

One-To-Many

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

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:

Defining The Inverse Of This Relation

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

Many-To-Many

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

$jd follows $mc:

Or using the attach() method:

The Cypher performed by this statement will be as follows:

$mc follows $jd back:

The Cypher performed by this statement will be as follows:

get the followers of $jd

The Cypher performed by this statement will be as follows:

Dynamic Properties

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:

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.

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:

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

Or detaching models:

Sync too:

Retrieving Polymorphic Relations

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

Dynamicly Loading Morph Model

Eager Loading Morph Model

Retrieving The Inverse of a Polymorphic Relation

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

Polymorphic Relations In Short

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

Eager Loading

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

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

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.

EdgeIn

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

To associate a User to a Location:

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:

EdgeOut

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

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

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

And fetch the related models:

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.

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.

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

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.

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.

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().

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:

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:

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:

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

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.

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

Or using the id of the model:

The Cypher for the query that attaches records would be:

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:make:migration create_user_label

Label migrations will be placed in app/database/labels

You can add additional options to commands like:

php artisan neo4j:make:migration foo --path=app/labels
php artisan neo4j:make:migration create_user_label --create=User
php artisan neo4j:make:migration 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.

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

Renaming Labels

Checking Label's Existence

Checking Relation's Existence

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

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 :confounded:

• 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:

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().