djangoproject

How #Django knows to #UPDATE vs. #INSERT when you call #save (), #Django follows this algorithm: If the object’s primary key attribute is set to a value that evaluates to True (i.e., a value other than None or the empty string), Django executes an UPDATE. If the object’s primary key attribute is not set or if the UPDATE didn’t update anything, Django executes an INSERT.

What happens when you #save within #django? 1- Emit a pre-save signal. 2- Preprocess the data. 3- Prepare the data for the database. 4- Insert the data into the database. 5- Emit a post-save signal.