Modify ruby hash in place( rails strong params)

permit returns a new hash with those keys in it, so you’re not modifying the real params variable. You’re also not saving a reference to the hash trip_params returns, so you get it fresh each call in save.

Try this:

def save
  tp = trip_params
  tp[:name] = 'Modifying name in place'
  # ... use tp later, it'll be in there
end

Or, if you really want it to be used the way you previously did, modify trip_params like so:

def trip_params
  @trip_params ||= params.require(:trip).permit(:name, :date)
end

Now that hash is lazily cached and the same one is returned on subsequent trip_params calls.