Ruby on Rails

notice.rb:

  has_one  :active_comment_relationship, class_name: "Commentrelationship",
                                         foreign_key: "commenter_id",
                                         dependent: :destroy
  has_one  :supernotice, through: :active_comment_relationship, source: :commentee
  accepts_nested_attributes_for :active_comment_relationship

_notice.html.erb:

    <%= form_tag( {controller: "notices", action: "create"}, method: "post", class: "comment_form", multipart: true ) do %>
      <%= hidden_field_tag :callsign, @character.callsign %>
      <%= hidden_field_tag "notice[active_comment_relationship][commentee_id]", notice.id %>
      .
      .

notices_controller.rb:

    @notice = @character.notices.build(notice_params)
    if @notice.save
      if !params[:notice][:active_comment_relationship][:commentee_id].nil? # THE OFFENDING LINE
        @notice.create_comment(params[:notice][:active_comment_relationship][:commentee_id])
      end
    end

    def notice_params
      params.require(:notice).permit( :content, :picture, :latitude, :longitude, active_comment_relationship_attributes: [:commentee_id] )
    end

The code above gives the following error:

undefined method `[]' for nil:NilClass

Sometimes a notice is submitted with a blank/nil :commentee_id, so I would have thought !params[:notice][:active_comment_relationship][:commentee_id].nil?

would have worked. How do I write this correctly? How do you correctly access nested parameters?