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A select_tag is 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")

    def new
      @campaign = Campaign.new

    def create
      @campaign = Campaign.new(campaign_params)

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

    def show
      @campaign = Campaign.includes(:uploadzip,


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

....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]",
                Uploadzip.all, :id, :file_name
                ), { include_blank: "Include a Zip File" } %>

    .....some more typical fields

<% end %>

Any help would be highly appreciated!