另一个->形式中的第一个参数不能包含nil或为空

如标题所示，我对微博有疑问。我真的不知道错误在哪里。关于此错误的其他帖子并没有真正解决我的问题，也没有给出解决方法的想法。

我正在尝试显示帖子并显示帖子创建框。

这是我所拥有的：

microposts_controller.rb

class MicropostsController < ApplicationController
      before_action :logged_in_user, only: [:create, :destroy]

      def create
        secure_post = params.require(:micropost).permit(:content)
        @micropost = current_user.microposts.build(secure_post) 
        if @micropost.save
          flash[:success] = "Micropost created!"
          redirect_to root_url
        else
          render 'static_pages/home'
        end
      end

      def destroy
      end
end

microposts_form.html.erb

<%= form_for (@micropost) do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="field">
    <%= f.text_area :content, placeholder: "Compose new micropost..." %>
  </div>
  <%= f.submit "Post", class: "btn btn-primary" %>
<% end %>

memes.html.erb

<% if logged_in? %>
  <div class="row">
    <aside class="col-md-4">
      <section class="user_info">
        <%= render 'shared/user_info' %>
      </section>
      <section class="micropost_form">
        <%= render 'shared/micropost_form' %>
      </section>
    </aside>
  </div>
<% end %>

确切错误： localhost：3000 / memes

我知道表格中的某处有NIL-但是应该在哪里以及如何将其固定？

Rails服务器：

    Started GET "/memes" for ::1 at 2015-12-07 22:46:48 +0000
  ActiveRecord::SchemaMigration Load (0.0ms)  SELECT "schema_migrations".* FROM "schema_migrations"
Processing by StaticPagesController#memes as HTML
  User Load (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1  [["id", 6]]
  CACHE (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1  [["id", 6]]
  CACHE (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1  [["id", 6]]
  CACHE (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1  [["id", 6]]
  CACHE (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1  [["id", 6]]
  CACHE (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1  [["id", 6]]
   (0.0ms)  SELECT COUNT(*) FROM "microposts" WHERE "microposts"."user_id" = ?  [["user_id", 6]]
  Rendered shared/_user_info.html.erb (312.2ms)
  Rendered shared/_micropost_form.html.erb (3.5ms)
  Rendered static_pages/memes.html.erb within layouts/application (439.6ms)
Completed 500 Internal Server Error in 464ms (ActiveRecord: 1.0ms)

ActionView::Template::Error (First argument in form cannot contain nil or be empty):
    1:  <%= form_for(@micropost) do |f| %>
    2:       <%= render 'shared/error_messages', object: f.object %>
    3:       <div class="field">
    4:         <%= f.text_area :content, placeholder: "Compose new micropost..." %>
  app/views/shared/_micropost_form.html.erb:1:in `_app_views_shared__micropost_form_html_erb__1950492356_78981080'
  app/views/static_pages/memes.html.erb:75:in `_app_views_static_pages_memes_html_erb___1961772234_79299460'


  Rendered C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/actionpack-4.2.2/lib/action_dispatch/middleware/templates/rescues/_source.erb (1.0ms)
  Rendered C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/actionpack-4.2.2/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb (2.0ms)
  Rendered C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/actionpack-4.2.2/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (1.0ms)
  Rendered C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/actionpack-4.2.2/lib/action_dispatch/middleware/templates/rescues/template_error.html.erb within rescues/layout (42.1ms)