ruby on rails - Affecting resulting params set from form_for -

relative newbie here ruby on rails.

using standard form_for method in view someobjcontroller#new action

= form_for @someobj |f|     .     .     .   %p.submits   = f.submit "submit", :class => "submit" 

a submission param[] array produced contains hash of @someobj fields set in form, such

param[someobj] => { "field1" => "val1", "field2" => "val2", ... } 

i prefer put different value, result of someobj.to_s param[someobj] someobjcontroller#create work with, such that

param[someobj] => "strvalfromtos" 

i doubt it's relative, in case, model underlying #new action not persistent in database (i.e., someobj not derived activerecord::base, though portions of activemodel included.)

i haven't had luck trying adjust until after #create invoked, submission #new #create want amend. it's not clear me if should focusing more on form_for statement or doing special in controller (i'm guessing form_for right focus).

and, yes, whole thing bit ocd of me, actual fieldnames long (appropriately model) data needed #create small.

is there relatively painless way this, assuming someobj.to_s has been written?

many thanks, richard

change

when submit form, controller receive params hash, you've stated (rails params explained?)

that means can change value in hash wish:

def create     #has access params hash     params[:owner][:key] = value end 

as create method receives hash object, you'll have change in here. because it's standard hash (which has been declared), should able alter required

add

if want add values params hash, can use .merge method, this:

def create     #has access params hash     params[:key].merge(user_id: current_user.id) end