How to add an extra value into a Rails param - ruby-on-rails

Question

I'm trying to solve a problem with getting all the values saved to my database. Here's how my application is setup is
before_filter :load_make, only: :create
def create
#record = #make.message.new(my_params)
#record.save
end
def load_make
make_id = params[:message] ? params[:message][:make_id] : params[:make_id]
#make = Car.find_by(custom_make: make_id)
#make ||= Car.find_by(id: make_id).tap
end
def my_params
params.require(:message).permit(:message_type, :message_date, :make_id)
end
My problem is that I want to create another method that does a GET request from a different API that returns a created_at date and also save it on create, similar to:
def lookup_car
Car.car_source.find(id: my_params[:make_id]).created_at
# returns a datetime value
end
I'm looking for advice on what's the best way to put this into the my_params method :message_date and save it along with everything else on the create action?
Schema for model:
create_table "messages", force: :cascade do |t|
t.integer "make_id"
t.string "message", limit: 255
t.datetime "created_at"
t.datetime "updated_at"
t.string "message_type", limit: 255
t.datetime "message_date"
end

Answer 1

Firstly, you should NOT really change / update / insert to the created_at since Rails does that for you. If anything, I suggest you adding another column.
Secondly, you should NOT do and create / update on a Get request.
Other than that, adding another field to your params is easy as long as you have that column ready. Not sure how your models are structure, but here you can do something along the line like this below. Let's say you have message_date column in your whatever model, you can do this:
def my_params
message_date_param = { message_date: Time.now }
params.require(:message).permit(:message_type, :message_date, :make_id).merge(message_date)
end

Answer 2

I wrote this pretty late at night when I probably wasn't making much sense, but essentially what I was wanting was to update another value at same time save was called on the #record. I solved this by using attributes, which updates but doesn't call save (since I was doing that already below).
For example:
def create
car = Car.car_source.find(id: my_params[:make_id]).created_at
#record.attributes = { message_date: car }
#record.save
end
Also much thanks to all the other comments. I've completely refactored this code to be more rails idiomatic.