modeltojson.py

import json
from django.core.management.base import BaseCommand, CommandError
from django.apps import apps

class Command(BaseCommand):
    help = 'Takes a model argument in the form of app_label.model_name and outputs all fields and values as JSON'
    
    def add_arguments(self, parser):
        parser.add_argument('model', nargs="1", help='A model argument in the form of app_label.model_name')

    def handle(self, *args, **options):
        # Get Model class and fields by input. Queries all instances of that model.
        app_label, model_name = options['model'].split('.')
        model_class = apps.get_model(app_label, model_name)
        model_fields = model_class._meta.get_fields()
        model_instances = model_class.objects.all()
        
        output = []
        
        for instance in model_instances:
            # Generate new dict for fields and values of each instance
            d = {}
            for field in model_fields:
                # Store instance attributes
                key = field.name
                try:
                    value = getattr(instance, field.name) 
                except AttributeError:
                    print("Error retrieving attribute for ", field.name, " of ", instance)
                d[key] = value
            output.append(d)
        return json.dumps(output)

# --- Sample Outputs ---

$ python manage.py modeltojson livetest.TestModel
[{"field2": false, "id": 1, "field3": "Hello", "field1": 1}, {"field2": true, "id": 2, "field3": "Hello", "field1": 1}]

$ python manage.py modeltojson livetest.TestModel2
[{"id": 1, "second_field": true, "third_field": "hello", "first_field": 1}]

$ python manage.py modeltojson testapp.SecondTest
[
  {"field3": false, "id": 1, "field1": "hello, world", "field2": 0}, 
  {"field3": false, "id": 2, "field1": "hello, world", "field2": 0}, 
  {"field3": false, "id": 3, "field1": "This is a charfield", "field2": 0}
]