title: Django: Adding model to ManyToMany by pk, without fetching
body: <p>I have model A with a ManyToMany to model B. I have a pk of an object of model B, and I want to add it to the ManyToManyField of an object of model A. Is it possible to add it without expending resources to fetch object b from the database? I already have its pk, can I add it without fetching? </p>