export_related_as_json gathers all instances related by foreign keys to what is being exported and exports them as well in a serialization bonanza.

export_related_as_json.py

'''
Original: http://www.djangosnippets.org/snippets/1611/
Author: johnboxall

The Django Admin Action documentation leads you through exporting a
queryset to JSON. However exporting from a single model rarely tells
the whole story.

Using the `CollectObjects` class, `export_related_as_json` gathers all
instances related by foreign keys to what is being exported and exports
them as well in a serialization bonanza.

Use it to export `Users` and you'll get their `Profile` objects as well!

Usage:
    # admin.py
    from django.contrib import admin

    admin.site.add_action(export_related_as_json)
'''

from django.core import serializers
from django.db.models.query import CollectedObjects
from django.http import HttpResponse

def export_related_as_json(modeladmin, request, qs):
    """Serializes the selected queryset and all related objects to JSON"""
    response = HttpResponse(mimetype="text/javascript")
    
    # Gather the related objects for each instance in the queryset.
    collected_objs = CollectedObjects()
    for obj in qs:
        obj._collect_sub_objects(collected_objs)
    
    # Collect all the instances into a list suitable for serialization.
    objs = []
    for _, objs_dict in collected_objs.items():  # co doesn't implement values
        objs += objs_dict.values()
        
    serializers.serialize("json", objs, stream=response, indent=4)
    return response