file_field

At: http://www.tutorialspoint.com/ruby-on-rails/rails-file-uploading.htm

You can find:

<%= file_field 'upload', 'datafile' %>

I saw the file_field documentation from here:

http://api.rubyonrails.org/classes/ActionView/Helpers/FormHelper.html#method-i-file_field

But, still cannot get how the parameters 'upload' and 'datafile' work.

Based on the documentation:

upload ---> object_name
datafile ---> method

How is that?

Can you clarify on this?

Thanks.