def get_model_or_404(app_name, model_name):
    """
    Attempt to get a model from the ``AppCache``
    and raise ``Http404`` if it cannot be found
    """
    from django.db.models import get_model
    from django.http import Http404
    
    model_class = get_model(app_name, model_name)
    
    if model_class is None:
        raise Http404("This model does not exist!")

    return model_class