I have gotten myself rather confused working with LiveView and I need some clarity.
I have a complex form with lots of interaction between components/fields. I am using embedded schemas. When I handle the phx-change event I take the params and produce a changeset. If valid I then start doing the heavy lifting – for instance a number of fields are calculated based on other fields.
So when I wrote the function to do these calculations, it takes the struct as an argument and returns a new “updated” struct. In fact, this function is in the schema module, e.g. def calculate(%__MODULE__{} = datastruct) ....
But for LiveView what I have is a changeset. I start out with a changeset, to ensure inputs are valid, and I have to end up with changeset, assigning it to the socket via to_form.
So my question is, should I be manipulating the data via the changeset, using fetch_field and put_change and the like rather than directly manipulating struct? Or should I apply the changeset up front, manipulate the struct it gives me, and then convert it back to a changeset at the end?
Note I have some embeds_many in there too, if that complicates matters.
