mvc: What is the best way to automatically fill a model with just one http request?

I am creating a system to configure work schedules, and I want to make a kind of "assistant", which will automatically create a certain number of work shifts per day in a work week.

I want this function to be a "one click" experience, with no need for configuration, so I do not want to return a view with a form (GET) first, and then publish the form so that it is saved in the db. But is not the general rule not to write in the database in the GET requests?

How would you do it?