错误消息拒绝显示[RoR]

好吧，我将尽力解释这一点。

我有一个TopicsController，它的内部有一个Show方法，该方法遍历主题模型并显示所有需要的信息，在它下面，我有一个帖子模型的表单。问题是。如果验证失败，则错误消息将拒绝显示。我已经尝试了一切，但我不知道该怎么办。我有一个应该工作的自定义错误部分。

控制器：

  def create
    @community_post.user_id = current_user.id
    @community_post.community_topic_id = params[:community_topic_id]

    if @community_post.save
      redirect_to "/community_topics/#{@community_post.community_topic_id}", notice: 'Community post was successfully created.'
    else
      redirect_to "/community_topics/#{@community_post.community_topic_id}", notice: 'Community post was NOT successfully created.'
      @community_post.community_topic_id = nil
    end
  end

看法：

<h1> Submit reply </h1>

<% @community_post  = CommunityPost.new %>

<%= form_for(@community_post) do |f| %>

    <%= render 'error_messages_posts' %>

    <%= f.label :text %>
    <%= f.text_area :text %>

    <%= hidden_field_tag :community_topic_id, @community_topic.id %>

    <br>

    <%= f.submit "Submit reply" %>
<% end %>

部分的：

    <% if @community_post.errors.any? %>
  <div id="error_explanation">
    <div class="alert alert-error">
      The form contains <%= pluralize(@community_post.errors.count, "error") %>.
    </div>
    <ul>
    <% @community_post.errors.full_messages.each do |msg| %>
      <li>* <%= msg %></li>
    <% end %>
    </ul>
  </div>
<% end %>