Question

我是Rails的新手，正在研究Getting Started Guide。我通读了this关于指南的类似问题，但似乎并不相关。

我被困在第6.3节，我们试图让用户在博文中添加评论。我已经在帖子显示视图中添加了一个评论表单，之前工作正常，但现在引发了以下错误。有什么问题？

NoMethodError in Posts#show

Showing /Users/.../Desktop/Rails Blog/blog/app/views/posts/show.html.erb where line #24 raised: 

undefined method `comments' for nil:NilClass



Extracted source (around line #24):

    21 <% end %>
    22 
    23 <h2>Add a comment:</h2>
    24 <%= form_for([@post, @posts.comments.build]) do |f| %>
    25    <p>
    26         <%= f.label :commenter %><br />
    27         <%= f.text_field :commenter %>

posts_controller.rb：

class PostsController < ApplicationController
    def index
        @posts = Post.all
    end
    def new
        @post = Post.new
    end
    def create
        @post = Post.new(params[:post].permit(:title, :text))
        if @post.save
            redirect_to @post
        else
            render 'new'
        end
    end
    def edit
        @post = Post.find(params[:id])
    end
    def update
        @post = Post.find(params[:id])

        if @post.update(params[:post].permit(:title, :text))
            redirect_to @post
        else
            render 'edit'
        end
    end
    def show
        @post = Post.find(params[:id])
    end
    def destroy
        @post = Post.find(params[:id])
        @post.destroy
        redirect_to posts_path
    end
    private
        def post_params
            params.require(:post).permit(:title, :text)
        end
end

comments_controller：

class CommentsController < ApplicationController
    def create
        @post = Post.find(params[:post_id])
        @comment = @post.comments.create(params[:comment].permit(:commenter, :body))
        redirect_to post
    end
end

posts.show.html.erb：

<p>
    <strong>Title:</strong>
    <%= @post.title %>
</p>

<p>
    <strong>Text:</strong>
    <%= @post.text %>
</p>

<h2>Comments</h2>
<% @post.comments.each do |comment| %>
    <p>
        <strong>Commenter:</strong>
        <%= comment.commenter %>
    </p>
    <p>
        <strong>Comment:</strong>
        <%= comment.body %>
    </p>
<% end %>

<h2>Add a comment:</h2>
<%= form_for([@post, @posts.comments.build]) do |f| %>
    <p>
        <%= f.label :commenter %><br />
        <%= f.text_field :commenter %>
    </p>
    <p>
        <%= f.label :body %><br />
        <%= f.text_area :body %>
    </p>
    <p>
        <%= f.submit %>
    </p>
<% end %>

<%= link_to 'Back', posts_path %>
<%= link_to 'Edit', edit_post_path(@post) %>

Answer 1

你有@posts。该变量称为@post。放下“s”。

Rails指南“未定义的方法'评论'为nil：NilClass”

1 个答案: