def register_app_activity():
    """
    Create watchers for models defined in settings.py.
    Once created, they will be passed over
    Activity.objects.follow_model(), which lives in managers.py
    """
    from django.conf import settings
    from django.contrib.contenttypes.models import ContentType
    from .models import Activity
    if not hasattr(settings, 'ACTIVITY_MONITOR_MODELS'):
        return
    for item in settings.ACTIVITY_MONITOR_MODELS:
        try:
            app_label, model = item['model'].split('.', 1)
            content_type = ContentType.objects.get(app_label=app_label,
                model=model)
            model = content_type.model_class()
            Activity.objects.follow_model(model)
        except ContentType.DoesNotExist:
            pass
