How can I properly use hidden_fields with ruby on rails to pass information to the controller?
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I am attempting to allow the user to press a button create a new entry into the database using a hidden_field. However, the one bit of information I do want passed to the database is not making it there.

form on the view

    <%= form_for(current_user.rounds.build(:round_id => '201202)) do |f| %>
        <div><%= f.hidden_field :round_id %></div>
        <%= f.submit "Register", class: "btn btn-large" %>
    <% end %>

controller

    def create
        @register = current_user.rounds.build(params[:round_id])
        if @register.save
            redirect_to root_path, :flash => { :success => "Registered" }
        end
    end

This code however creates a new entry in the database with a user_id but no round_id.

Can someone show me where my mistake is?

Thanks
    