Django Neomodel (beta!)

neomodel

This module allows you to use the neo4j graph database with Django using neomodel

Warnings

Admin functionality is very experimental. Please see todos / issues here

Live Examples (add yours here)

Syracuse: a database of company linkages created from unstructured text. Repo at syracuse-neo

Getting started

Install the module:

$ pip install django_neomodel

Add the following settings to your settings.py:

NEOMODEL_NEO4J_BOLT_URL = os.environ.get('NEO4J_BOLT_URL', 'bolt://neo4j:foobarbaz@localhost:7687')

# Make sure django_neomodel comes before your own apps
INSTALLED_APPS = (
    # django.contrib.auth etc
    'django_neomodel',
    'yourapp'
)

Write your first node definition in yourapp/models.py:

from neomodel import StructuredNode, StringProperty, DateProperty

class Book(StructuredNode):
    title = StringProperty(unique_index=True)
    published = DateProperty()

Create any constraints or indexes for your labels. This needs to be done after you change your node definitions much like manage.py migrate:

$ python manage.py install_labels

Now in a view yourapp/views.py:

from .models import Book

def get_books(request):
    return render('yourapp/books.html', request, {'books': Book.nodes.all()})

In your yourapp/admin.py:

from django_neomodel import admin as neo_admin
from .models import Book

class BookAdmin(dj_admin.ModelAdmin):
    list_display = ("title", "created")
neo_admin.register(Book, BookAdmin)

And you're ready to go. Don't forget to check the neomodel_ documentation.

Model forms

Switch the base class from StructuredNode to DjangoNode and add a 'Meta' class:

from datetime import datetime
from django_neomodel import DjangoNode
from neomodel import StructuredNode, StringProperty, DateTimeProperty, UniqueIdProperty

class Book(DjangoNode):
    uid = UniqueIdProperty()
    title = StringProperty(unique_index=True)
    status = StringProperty(choices=(
            ('Available', 'A'),
            ('On loan', 'L'),
            ('Damaged', 'D'),
        ), default='Available')
    created = DateTimeProperty(default=datetime.utcnow)

    class Meta:
        app_label = 'library'

Create a model form class for your DjangoNode:

class BookForm(ModelForm):
    class Meta:
        model = Book
        fields = ['title', 'status']

This class may now be used just like any other Django form.

Settings

The following config options are available in django settings (default values shown). These are mapped to neomodel.config as django is started:

NEOMODEL_NEO4J_BOLT_URL = 'bolt://neo4j:neo4j@localhost:7687'
NEOMODEL_SIGNALS = True
NEOMODEL_FORCE_TIMEZONE = False
NEOMODEL_MAX_CONNECTION_POOL_SIZE = 50

Signals

Signals work with DjangoNode sub-classes:

from django.db.models import signals
from django_neomodel import DjangoNode
from neomodel import StringProperty

class Book(DjangoNode):
  title = StringProperty(unique_index=True)

def your_signal_func(sender, instance, signal, created):
    pass

signals.post_save.connect(your_signal_func, sender=Book)

The following are supported: pre_save, post_save, pre_delete, post_delete. On freshly created nodes created=True in the post_save signal argument.

Testing

You can create a setup method which clears the database before executing each test:

from neomodel import db, clear_neo4j_database

class YourTestClass(DjangoTestCase):
    def setUp(self):
        clear_neo4j_database(db)

    def test_something(self):
        pass

Management Commands

The following django management commands have been included.

install_labels

Setup constraints and indexes on labels for your node definitions. This should be executed after any schema changes:

$ python manage.py install_labels
Setting up labels and constraints...

Found tests.someapp.models.Book
+ Creating unique constraint for title on label Book for class tests.someapp.models.Book
Finished 1 class(es).

clear_neo4j

Delete all nodes in your database, warning there is no confirmation!

Requirements

Python 3.8+
neo4j 5.x, 4.4 (LTS)

Docker Example

Using Docker Compose.

Commands to setup Docker Container docker-entrypoint.sh:

# Go to tests
$ cd tests/
# Docker Command (Make sure Docker is running and up to date)
$ docker-compose up
# login in admin with username=admin password=1234

Go to http://localhost:7474/browser/

Go to http://localhost:8000/admin/

Running Tests

Setup Neo4j Desktop with a local database with password 'foobarbaz' and version 5.x or 4.4.x (Neo4j LTS version).

Commands to run tests:

# create local venv and install dependencies.
$ pip install -e '.[dev]'; export DJANGO_SETTINGS_MODULE=tests.settings;
$ tests/manage.py install_labels
$ tests/manage.py migrate
$ pytest

# example output:

platform darwin -- Python 3.9.0, pytest-6.1.2, py-1.9.0, pluggy-0.13.1
pick 0900469 Neo4J-update-t-4.1
collected 16 items

someapp/tests/test_atomicity.py .                                                                                                                                                                                                                      [  6%]
someapp/tests/test_commands.py ..                                                                                                                                                                                                                      [ 18%]
someapp/tests/test_model_form.py ...........                                                                                                                                                                                                           [ 87%]
someapp/tests/test_sanity.py .                                                                                                                                                                                                                         [ 93%]
someapp/tests/test_signals.py .
16 passed, 11 warnings in 1.62s