List all signals by model and signal type. Tested with Django 1.9 and MongoEngine

list_all_model_signals.py

# coding:utf-8

import ctypes
import gc
import inspect
from collections import defaultdict

import re
from blinker import NamedSignal
from django.core.management.base import BaseCommand
from django.db.models.signals import m2m_changed, pre_migrate, post_migrate, ModelSignal, pre_init, post_init, pre_save, post_save, pre_delete, post_delete
from mongoengine.signals import pre_init as m_pre_init, post_init as m_post_init, pre_save as m_pre_save, pre_save_post_validation as m_pre_save_post_validation, \
    post_save as m_post_save, pre_delete as m_pre_delete, post_delete as m_post_delete, pre_bulk_insert as m_pre_bulk_insert, post_bulk_insert as m_post_bulk_insert

try:
    from django.dispatch.dispatcher import WEAKREF_TYPES
except ImportError:
    import weakref

    WEAKREF_TYPES = weakref.ReferenceType,

signal_print_template = '{module}.{name} #{line}'

SIGNAL_NAMES = {
    pre_init: 'pre_init',
    post_init: 'post_init',
    pre_save: 'pre_save',
    post_save: 'post_save',
    pre_delete: 'pre_delete',
    post_delete: 'post_delete',
    m2m_changed: 'm2m_changed',
    pre_migrate: 'pre_migrate',
    post_migrate: 'post_migrate',
    m_pre_init: 'mongo_pre_init',
    m_post_init: 'mongo_post_init',
    m_pre_save: 'mongo_pre_save',
    m_pre_save_post_validation: 'mongo_pre_save_post_validation',
    m_post_save: 'mongo_post_save',
    m_pre_delete: 'mongo_pre_delete',
    m_post_delete: 'mongo_post_delete',
    m_pre_bulk_insert: 'mongo_pre_bulk_insert',
    m_post_bulk_insert: 'mongo_post_bulk_insert'
}

match_classname = re.compile(b"^<class '([^']*)'>$")


class Command(BaseCommand):
    help = 'List all signals by model and signal type'

    def handle(self, *args, **options):
        signals = [obj for obj in gc.get_objects() if isinstance(obj, ModelSignal) or isinstance(obj, NamedSignal)]
        models = defaultdict(lambda: defaultdict(list))

        for signal in signals:
            signal_name = SIGNAL_NAMES.get(signal, 'unknown')
            try:
                receivers = signal.receivers.items()
            except AttributeError:
                # list has no attribute items
                receivers = signal.receivers
            for receiver in receivers:
                lookup, receiver = receiver
                if isinstance(receiver, WEAKREF_TYPES):
                    receiver = receiver()
                if receiver is None:
                    continue
                try:
                    receiver_id, sender_id = lookup
                except TypeError:
                    sender_id = lookup

                model = ctypes.cast(sender_id, ctypes.py_object).value
                try:
                    line = inspect.getsourcelines(receiver)[1]
                    path = inspect.getsourcefile(receiver)
                    module = receiver.__module__
                    name = receiver.func_name
                except TypeError:
                    func = receiver.weak_func()
                    cls = receiver.weak_self()
                    line = inspect.getsourcelines(func)[1]
                    path = inspect.getsourcefile(func)
                    module = "%s.%s" % (cls.__module__, cls.__name__)
                    name = func.func_name
                models[model][signal_name].append(signal_print_template.format(
                    name=name, module=module, line=line, path=path)
                )
        print ""
        print "Signals ---------------------"
        print ""
        for key in sorted(models.keys()):
            if key is not None:
                print '' + key.__module__ + "." + key.__name__
            for signal_name, lines in models[key].iteritems():
                print " " * 4, signal_name
                for line in lines:
                    print " " * 8, line