Ruby on rails RubyonRails入门教程中的注释错误

我正在通过官方网站上的入门教程学习RubyonRails

我唯一改变的是post-url映射指向/post/friendly-url，而不是/post/id

一切都很顺利，直到我尝试在帖子中添加评论，我收到以下错误

CommentsController中的命名错误#创建 这是我的密码

/app/controllers/comments\u controller.rb /apps/models/post.rb

class Posttrue
验证：content，：presence=>true
验证：友好，：存在=>true
验证：摘录，：presence=>true
验证：friendly，：with=>/^[^]的格式+$/
有很多：注释，：依赖=>：销毁
有很多：标签
接受：标记的\u嵌套的\u属性，\u，：允许\u销毁=>:true，
：如果=>proc{attrs}attrs.all{{k，v{v.blank？}
def至_参数
友好的
结束
结束

---

对不起，如果这是太多的信息，也请让我知道，如果我错过了什么。我什么都试过了，却找不到问题所在。提前感谢。

问题是您在

CommentController#create

中的

@post

是

nil

。也就是说，您提供的

参数[：id]

不正确，或者在数据库中找不到。我建议检查日志以查看

params[：id]

包含的内容，并查看是否与

find\u by\u-friendly

所期望的内容相匹配

如果

参数[：id]

看起来正确，我会使用rails控制台来尝试

帖子。通过友好的
查找并传入一些值，看看这是否适合您

如果
params[：id]
值看起来不正确，那么您的
form\u for（）
调用
comments/\u form.html.erb
可能是错误的，查看友好插件的文档，了解如何进行正确调用。
我已经通过查看日志验证了帖子是否传递空值，但我无法理解为什么在我添加评论时应用程序没有提交帖子信息。您的评论控制器似乎没有设置@post，所以我不确定它会在comments/_form.html.erb中使用什么？
undefined method `comments' for nil:NilClass
app/controllers/comments_controller.rb:7:in `create'

class CommentsController < ApplicationController
    def create
        @post = Post.find_by_friendly(params[:id])
        @comment = @post.comments.create(params[:comment])
        redirect_to post_path(@post)
    end

    def destroy
        @post = Post.find_by_friendly(params[:id])
        @comment = @post.comments.find(params[:id])
        @comment.destroy
        redirect_to post_path(@post)
    end
end

class Comment < ActiveRecord::Base
    belongs_to :post

    attr_accessible :body, :commenter

    validates :body,  :presence => true
    validates :commenter,  :presence => true
end

<%= form_for([@post, @post.comments.build]) do |f| %>

<%= f.label :commenter, "Your Name:" %>
    <%= f.text_field :commenter, :placeholder => "Your Name..." %>
<span class="help-block">What would you like to be called.</span><br/>

<%= f.label :body, "Your Comment:" %>
    <%= f.text_area :body, :size => "60x12", :placeholder => "Your Comment..." %>
<span class="help-block">What's on your mind?</span><br/>

    <%= f.submit %>

<% end %>

<% @post.tags.build %>
<%= form_for(@post) do |post_form| %>
<legend>Post Form</legend>
<% if @post.errors.any? %>
    <div id="error_explanation">
        <h2 class="text-error"><%= pluralize(@post.errors.count, "error") %> prohibited this post from being saved:</h2>
        <ul>
            <% @post.errors.full_messages.each do |msg| %>
                <li class="text-error"><%= msg %></li>
            <% end %>
        </ul>
    </div>
<% end %>

<%= post_form.label :name, "Post Name:" %>
    <%= post_form.text_field :name, :placeholder => "Post Name..." %>
<span class="help-block">The title of the article.</span><br/>

<%= post_form.label :friendly, "Friendly URL:" %>
    <%= post_form.text_field :friendly, :placeholder => "Friendly URL..." %>
<span class="help-block">SEO friendly URL displayed as /posts/post-name.</span><br/>

<%= post_form.label :content, "Post Content:" %>
<%= post_form.text_area :content, :size => "60x12", :placeholder => "Main Content..." %>
<span class="help-block">HTML enabled article content.</span><br/>

<%= post_form.label :excerpt, "Post Excerpt:" %>
    <%= post_form.text_area :excerpt, :placeholder => "Post Excerpt..." %>
<span class="help-block">Description of post for index page. No HTML.</span><br/>

<h2>Tags</h2>
<%= render :partial => 'tags/form',
    :locals => {:form => post_form} %><br/>

    <%= post_form.submit %>

<% end %>

Nullpulse::Application.routes.draw do
    resources :posts do
        resources :comments
    end

    root :to => "home#index"
end

class Post < ActiveRecord::Base
    attr_accessible :content, :friendly, :name, :excerpt, :tags_attributes

    validates :name,  :presence => true
    validates :content, :presence => true
    validates :friendly, :presence => true
    validates :excerpt, :presence => true
    validates_format_of :friendly, :with => /^[^ ]+$/

    has_many :comments, :dependent => :destroy
    has_many :tags

    accepts_nested_attributes_for :tags, :allow_destroy => :true,
        :reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } }

    def to_param
        friendly
    end
end