update_if_changed

gistfile1.py

def update_if_changed(model_instance, new_values):
    has_changed = False
    for field_name, field_value in new_values.items():
        old_value = getattr(model_instance, field_name)
        if old_value != field_value:
            setattr(model_instance, field_name, field_value)
            has_changed = True
    if has_changed:
        model_instance.save()