title: Angular - submitting a form when not all the fields are from user input
body: <p>I just learned about Angular forms and I managed to make a login one and a registration one from a tutorial, and those ones were easy enough. But now I want to make a form where not all the fields (table entries) need to be entered by the user, and I’m so new to this I don’t even know if it’s possible.</p>
  <p>So, for example, let’s say I have built a social media app, and the user logs in and then makes a post of some kind. Naturally, the post would go in a separate database table from the users table, where the content of the post would be stored, but also who made it. So, if I can get the content of the post from what the user types in the form, how do I access information about the user before submitting the form? Or is it possible to “add” it after?