DJANGO SCAFFOLD

This is a django scaffold with an SQL based model and a neomodel graph model. It is made to zoom in on the problem in neomodel between the versions 3.2.9 and 3.3.0 in combination with django.

It is made to support issue neo4j-contrib/neomodel#378

INSTALLATION

To install and make it work follow this

When using pipenv

On the bash shell do:

• pipenv install --three
• pipenv shell

When using pip

On the bash shell:

• virtualenv venv --python=python3
• . venv/bin/activate
• pip install -r requrements.txt

Installing database

When you activated the virtual environment

• ./manage.py migrate
• ./manage.py createsuperuser
• provide superuser name, email and pass
• start the server with: ./manage.py runserver
  • when using Pycharm, a Run server command is provided and can be used to start or debug the running server.
• navigate to link provided in your favorite webbrowser: http://127.0.0.1:8000

Installing labels for neomodel

In the activated virtual environment.

• neomodel_install_labels neoworld/models.py --db bolt://neo4j:<PASSWORD>@localhost:7687

Switch between neomodel versions

Depends if you use pip or pipenv, alter the requirements.txt (for pip) or Pipfile to switch to different version of neomodel.

Configuration of django for use with neomodel

• The package django-neomodel is not used. So you experience pure behaviour of neomodel (just as any other python to neo4j using neomodel implementation)
• The configuration is performed in config/settings.py.

# Neomodel config
# https://neomodel.readthedocs.io/en/latest/getting_started.html
from neomodel import config as neoconfig
neoconfig.DATABASE_URL = 'bolt://neo4j:<PASSWORD>@localhost:7687'

• The neomodel is defined in neoworld/models.py. It implements the Tutorial code.

Error when using neomodel 3.3.0

• switch to neomodel version 3.3.0
• restart the server
• ensure you already have some models loaded
• list all person objects using:

[24/Jan/2019 12:32:42] "GET / HTTP/1.1" 200 1676
Internal Server Error: /persons/
Traceback (most recent call last):
  File "~/.local/share/virtualenvs/django_neo_3.3.0-F55v51Sh/lib/python3.6/site-packages/neomodel/util.py", line 150, in _object_resolution
    resolved_object = self._NODE_CLASS_REGISTRY[frozenset(a_result_attribute[1].labels)].inflate(
KeyError: frozenset({'Person'})

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "~/.local/share/virtualenvs/django_neo_3.3.0-F55v51Sh/lib/python3.6/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "~/.local/share/virtualenvs/django_neo_3.3.0-F55v51Sh/lib/python3.6/site-packages/django/core/handlers/base.py", line 126, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "~/.local/share/virtualenvs/django_neo_3.3.0-F55v51Sh/lib/python3.6/site-packages/django/core/handlers/base.py", line 124, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "~/dev/django_neo_3.3.0/neoworld/views.py", line 18, in index
    latest_persons = Person.nodes.all()
  File "~/.local/share/virtualenvs/django_neo_3.3.0-F55v51Sh/lib/python3.6/site-packages/neomodel/match.py", line 469, in all
    return self.query_cls(self).build_ast()._execute()
  File "~/.local/share/virtualenvs/django_neo_3.3.0-F55v51Sh/lib/python3.6/site-packages/neomodel/match.py", line 445, in _execute
    results, _ = db.cypher_query(query, self._query_params, resolve_objects=True)
  File "~/.local/share/virtualenvs/django_neo_3.3.0-F55v51Sh/lib/python3.6/site-packages/neomodel/util.py", line 32, in wrapper
    return func(self, *args, **kwargs)
  File "~/.local/share/virtualenvs/django_neo_3.3.0-F55v51Sh/lib/python3.6/site-packages/neomodel/util.py", line 202, in cypher_query
    results = self._object_resolution(results)
  File "~/.local/share/virtualenvs/django_neo_3.3.0-F55v51Sh/lib/python3.6/site-packages/neomodel/util.py", line 162, in _object_resolution
    raise ModelDefinitionMismatch(a_result_attribute[1], self._NODE_CLASS_REGISTRY)
neomodel.exceptions.ModelDefinitionMismatch: Node with labels Person does not resolve to any of the known objects

Credits

• @jberends / Jan 2019

LICENSE

• The Unlicense - http://unlicense.org - see LICENSE