models.py

from django.db import models
from django.core.serializers.python import Serializer


class Tag(models.Model):
    name = models.CharField(primary_key=True, max_length=32)

    def __str__(self):
        return f'{self.name}'


class Resource(models.Model):
    title = models.CharField(max_length=256)
    url = models.URLField()
    tags = models.ManyToManyField(Tag)

    def __str__(self):
        return f'{self.title}'


class Connection(models.Model):
    REFERENCE = 'REF'
    relation_choices = (
        (REFERENCE, 'Reference'),
    )
    relation = models.CharField(max_length=3, choices=relation_choices)
    source = models.ForeignKey(Resource, models.CASCADE, related_name='source')
    target = models.ForeignKey(Resource, models.CASCADE, related_name='target')

    def __str__(self):
        return f'{self.source.name} -{self.relation}-> {self.target.name}'

    class Meta:
        unique_together = ('source', 'target', 'relation')
        ordering = ['source', 'target']

views.py

from django.http.response import JsonResponse

from network.models import Resource, Connection
from django.core.serializers import serialize


def network(request):
    nodes = Resource.objects.all().prefetch_related('tags')
    links = Connection.objects.all()
    return JsonResponse({
        'nodes': serialize('python', nodes),
        'links': serialize('python', links),
    })