nil：NilClass的未定义方法`events'

我正在使用嵌套属性，直到提交信息并收到此错误之前，一切似乎都还不错。它说它在我的EventsController文件中：

class EventsController < ApplicationController

    def new
        @event = Event.new
        @event.songs.build
    end

    def index
        @songs = Song.all
    end

    def show
      @event = Event.find(params[:id])
      @songs = @event.songs.paginate(page: params[:page])
    end

    def create
        @event = current_user.events.build(event_params)
        if @event.save
            flash[:success] = "Event Created!"
            redirect_to user_path(@event.user)
        else
            render 'welcome#index'
        end
    end

    def destroy
    end

    private 

      def event_params
        params.require(:event).permit(:name, :partycode, song_attributes: [:event_id, :artist, :title, :genre, :partycode])
      end
end

这是我的歌曲视图中的new.html.erb文件（根据选定事件处理歌曲提交）

<br>
<br>
<div class ="container">
  <div class="jumbotron">
  <%= form_for Event.new do |f| %>
    <h3>Enter a song:</h3>
    <%= f.fields_for :songs, Song.new do |song_form| %>

      <%= song_form.collection_select(:event_id, Event.all, :id, :name) %>
      <%= song_form.text_field :artist, placeholder: "Artist" %>
      <%= song_form.text_field :title,  placeholder: "Title" %>
      <%= song_form.text_field :genre,  placeholder: "Genre" %>
    <% end %>
    <%= link_to_add_fields "Add Song", f, :songs %>
    <%= f.text_field :partycode %>
    <%= f.submit "Submit", class: "btn btn-primary" %>
  <% end %>
  </div>
</div>

link_to_add_fields方法在我的ApplicationHelper.rb文件中定义：

module ApplicationHelper
  def link_to_add_fields(name, f, association)
    new_object = f.object.send(association).klass.new
    id = new_object.object_id
    fields = f.fields_for(association, new_object, child_index: id) do |builder|
      render("songs_fields", f: builder)
    end
    link_to(name, '#', class: "add_fields", data: {id: id, fields: fields.gsub("\n", "")})
  end
end

在session_helper.rb文件中定义了current_user：

module SessionsHelper

  # Logs in the given user.
  def log_in(user)
    session[:user_id] = user.id
  end

  def createEvent(event)
    session[:event_id] = event.id
  end



  # Returns the current logged-in user (if any).
  def current_user
    @current_user ||= User.find_by(id: session[:user_id])
  end
  # Returns true if the user is logged in, false otherwise.
  def logged_in?
    !current_user.nil?
  end

  def log_out
    session.delete(:user_id)
    @current_user = nil
  end

end

最后，这是我的songs_fields文件，该文件仅在用户单击显示“添加歌曲”的链接时才生成字段

<fieldset>  
  <%= f.text_field :artist, placeholder: "Artist" %>
  <%= f.text_field :title,  placeholder: "Title" %>
  <%= f.text_field :genre,  placeholder: "Genre" %>
</fieldset>

我觉得这是我使应用程序中的所有功能正常工作之前的最后一部分！因此，对此的帮助将是巨大的：D