Select_tag not saving associated child-object

I have a form with a select_tag and options_from_collection_for_select
that I can't seem to get to pass. The parent object, "Campaign", saves
but does not associate with the child-object "Uploadzip".

Campaign has_one Uploadzip
Uploadzip belongs_to Campaign

There's also the campaign_id foreign_key on the Uploadzips table.

Here's my Campaign controller:

class CampaignsController < ApplicationController
    def index
      @campaigns = Campaign.all.order("created_at DESC")
    end

    def new
      @campaign = Campaign.new
    end

    def create
      @campaign = Campaign.new(campaign_params)

      if @campaign.save
        flash[:success] = "Campaign Successfully Launched!"
        redirect_to @campaign
      else
        flash[:error] = "There was a problem launching your Campaign."
        redirect_to new_campaign_path
      end
    end

    def show
      @campaign = Campaign.includes(:uploadzip,
:uploadpdfs).find(params[:id])
    end

  private

    def campaign_params
      params.require(:campaign).permit(:name, :comment, :campaign_id,
uploadpdf_ids: [])
    end
end

....and the form...

<%= form_for @campaign, url: {action: "create"} do |f| %>

    .....some typical fields..

    <%= f.label :data_file, class: "right-label" %>

    <%= select_tag "uploadzip[campaign_id]",
                options_from_collection_for_select(
                Uploadzip.all, :id, :file_name
                ), { include_blank: "Include a Zip File" } %>

    .....some more typical fields

<% end %>

Any help would be highly appreciated!

Member of a FaceBook group helped me figure it out by adding a little
extra logic in the controller save.

      if @campaign.save

        zip = Uploadzip.find(params[:uploadzip_id])
      zip.campaign = @campaign
      zip.save

        flash[:success] = "Campaign Successfully Launched!"
        redirect_to @campaign
      else
        flash[:error] = "There was a problem launching your Campaign."
        redirect_to new_campaign_path
      end

This was met with changing the select_tag's name to..

                <%= select_tag :uploadzip_id,
            options_from_collection_for_select(
      Uploadzip.all, :id, :file_name
      ), { include_blank: "Include a Zip File" } %>