Django management command to dump objects to JSON with all nested relations included.

dumpnested.py

"""
    Dump out objects and all nested associations.
"""
import sys

from django.apps import apps
from django.contrib.admin.utils import NestedObjects
from django.core import serializers
from django.core.management import BaseCommand
from django.db import router
from django.db.models import Model


class Command(BaseCommand):

    def add_arguments(self, parser):
        parser.add_argument('args', metavar='[app_label.ModelName.id1,id2,id3...]', nargs='*',
                            help='Specify assessments by their ID.')
        parser.add_argument('--indent', default=None, dest='indent', type=int,
                            help='Specifies the indent level to use when pretty-printing output.')

    def handle(self, *args, **options):
        indent = options.get('indent')

        self.items = []

        for arg in args:
            app_label, model, ids = arg.split('.')
            app_config = apps.get_app_config(app_label)
            Model = app_config.get_model(model)
            for id in ids.split(','):
                self.dump_object(Model.objects.filter(pk=id))

        serializers.serialize('json',
                              self.items,
                              indent=indent,
                              stream=sys.stdout)

    def dump_object(self, obj):
        using = router.db_for_write(obj.__class__)

        collector = NestedObjects(using=using)
        collector.collect(obj)

        objs = collector.nested(lambda x: x)

        objs = list(zip(objs[::2], objs[1::2]))

        self.get_objects(objs)

    def get_objects(self, item):
        if isinstance(item, Model):
            self.items.append(item)
        elif isinstance(item[0], Model):
            for _item in item:
                self.get_objects(_item)
        else:
            for obj, children in item:
                self.items.append(obj)
                # items.append(obj)
                self.get_objects(children)