中間テーブルが保存されずタグを配列として表示できない

[1] pry(#<UploadsController>)> UploadTagRelation.create
=> #<UploadTagRelation:0x00007fdb13f9cdb0 id: nil, upload_id: nil, tag_id: nil, created_at: nil, updated_at: nil>
[2] pry(#<UploadsController>)> params[:upload_form][:name]
=> "東京 渋谷 カフェ"
[3] pry(#<UploadsController>)> 

NameError in UploadsController#create
undefined local variable or method `tag' for #<UploadForm:0x00007fdb25ceff38 @errors=#<ActiveModel::Errors:0x00007fdb25ced7b0 @base=#<UploadForm:0x00007fdb25ceff38 ...>, @errors=[]>, @title="カフェ", @text="タグカフェ", @url="", @working_day="", @day_off="", @cafe_wifi_id="1", @cafe_charging_id="1", @cafe_smoking_id="1", @image=#<ActionDispatch::Http::UploadedFile:0x00007fdb13eb42e0 @tempfile=#<Tempfile:/var/folders/gw/k3mqyqh15y37h56g1b17ymvc0000gn/T/RackMultipart20210514-85259-f73ob5.jpeg>, @original_filename="2f211d6f387d6006a68f.jpeg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"upload_form[image]\"; filename=\"2f211d6f387d6006a68f.jpeg\"\r\nContent-Type: image/jpeg\r\n">, @name="東京 渋谷 カフェ", @user_id=1, @validation_context=nil>
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Extracted source (around line #32):
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    end
    UploadTagRelation.create(upload_id: upload.id, tag_id: tag.id)⇦この部分
  end
end

 tag_list = params[:upload_form][:name].split(",")
    if @upload.valid?
      @upload.save(tag_list)⇦この部分
      redirect_to root_path
    else
      render new

class UploadsController < ApplicationController
  def index
    @uploads = Upload.all.order(created_at: :desc)
  end

  def new
    @upload = UploadForm.new
  end

  def create
    # binding.pry
    @upload = UploadForm.new(upload_params)
    tag_list = params[:upload_form][:name].split(",")
    if @upload.valid?
      @upload.save(tag_list)
      redirect_to root_path
    else
      render new
    end
  end

  def show
    @upload = Upload.find(params[:id])
    @tag = @upload.tags
  end

  def destroy
    @upload = Upload.find(params[:id])
    @upload.image.purge if @upload.image.attached?
    if @upload.destroy
      redirect_to root_path
    else
      render :show
    end
  end

  private

  def upload_params
    params.require(:upload_form).permit(:title, :text, :url, :working_day, :day_off, :cafe_wifi_id, :cafe_charging_id, :cafe_smoking_id, :image, :name).merge(user_id: current_user.id)
  end
end

class UploadForm
  include ActiveModel::Model
  attr_accessor :title, :text, :url, :working_day, :day_off, :cafe_wifi_id, :cafe_charging_id, :cafe_smoking_id,
                :user_id, :image, :name

  with_options presence: true do
    validates :title
    validates :text
    validates :cafe_wifi_id
    validates :cafe_charging_id
    validates :cafe_smoking_id
    validates :user_id
    validates :image
    validates :name
  end

  with_options numericality: { other_than: 0 } do
    validates :cafe_wifi_id
    validates :cafe_charging_id
    validates :cafe_smoking_id
  end

  def save(tag_list)
    upload = Upload.create(title: title, text: text, url: url, working_day: working_day, day_off: day_off, cafe_wifi_id: cafe_wifi_id, cafe_charging_id: cafe_charging_id, cafe_smoking_id: cafe_smoking_id, user_id: user_id, image: image)
    # tag = Tag.create(name: name)

    tag_list.each do |tag_name|
      tag = Tag.where(name: tag_name).first_or_initialize
      tag.save
    end

    UploadTagRelation.create(upload_id: upload.id, tag_id: tag.id)
  end
end

class Upload < ApplicationRecord
  has_one_attached :image
  has_one :map
  belongs_to :user
  has_many :upload_tag_relations, dependent: :destroy
  has_many :tags, through: :upload_tag_relations, dependent: :destroy
  extend ActiveHash::Associations::ActiveRecordExtensions
  belongs_to :cafe_smoking
  belongs_to :cafe_charging
  belongs_to :cafe_wifi
end

class UploadTagRelation < ApplicationRecord
  belongs_to :tag
  belongs_to :upload
end

class Tag < ApplicationRecord
  has_many :upload_tag_relations
  has_many :uploads, through: :upload_tag_relations

  validates :name, uniqueness: true
end