Question

我有典型的文章和评论博客格式。这是典型的has_many / belongs_to，即指南的博客类型。

但是，我正在尝试编辑文章中的评论，而且我对于为此构建正确的表单毫无头绪。

这也是一个让我更复杂的部分。

任何帮助和/或教育我都会受到赞赏。

评论模型

class Comment < ApplicationRecord
  belongs_to :article
end

文章的模型

class Article < ApplicationRecord

    has_many :comments

    validates :title, presence: true, length: { minimum: 5} 

end

文章的显示页面

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

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

<h2>Comments</h2>
<%= render @article.comments %>

<h2>Add a comment:</h2>
<%= render 'comments/form' %>

<%= link_to 'Edit', edit_article_path(@article) %> |
<%= link_to 'Back', articles_path %>

评论的_comment.html.erb页面

<p>
  <strong>Commenter:</strong>
  <%= comment.commenter %>
</p>

<p>
  <strong>Comment:</strong>
  <%= comment.body %>
</p>


<p>
  <%= link_to 'Destroy Comment', [comment.article, comment],
               method: :delete,
               data: { confirm: 'Are you sure?' } %>
</p>

<p>
    <%= link_to 'Edit', edit_article_comment_path(@article, comment) %>
</p>

评论的_form.html

<%= form_for([@article, @comment]) 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 %>

错误

来自评论的_form.html.erb页面，引用此行：<%= form_for([@article, @comment]) do |f| %> ...错误为：First argument in form cannot contain nil or be empty ...

文章控制器

class ArticlesController < ApplicationController


    def index
        @articles = Article.all 
    end


    def new
        @article = Article.new
    end

    def edit 
        @article = Article.find(params[:id])
    end

    def create
        #render plain: params[:article].inspect
        #@article = Article.new(params[:article])
        #@article = Article.new(params.require(:article).permit(:title, :text))
        @article = Article.new(article_params)

        if @article.save 
            redirect_to @article 
        else
            render 'new'
        end
    end

    def update 
        @article = Article.find(params[:id])

        if @article.update(article_params)
            redirect_to @article 
        else
            render 'edit'
        end
    end


    def show 
        @article = Article.find(params[:id])
    end

    def destroy 
        @article = Article.find(params[:id]) 
        @article.destroy 

        redirect_to articles_path 
    end


    private 
        def article_params
            params.require(:article).permit(:title, :text)
        end

end

评论控制器

class CommentsController < ApplicationController
  def create
    @article = Article.find(params[:article_id])
    @comment = @article.comments.create(comment_params)
    redirect_to article_path(@article)
  end

  def destroy 
    @article = Article.find(params[:article_id])
    @comment = @article.comments.find(params[:id])
    @comment.destroy 
    redirect_to article_path(@article) 
  end

  private
    def comment_params
      params.require(:comment).permit(:commenter, :body)
    end
end

Answer 1

表单中的第一个参数不能包含nil或为空

错误是由于@article和@comment在表单中为零。由于您使用局部渲染表单，因此您需要将变量发送到部分

将<%= render 'comments/form' %>更改为<%= render 'comments/form', article: @article, comment: @comment %>

并且在表单中有<%= form_for([article, comment]) do |f| %>

同样在文章控制器的show方法中，您应该定义@comment

def show 
  @article = Article.find(params[:id])
  @comment = Comment.new
end

如何在文章的页面中编辑评论 - 不断收到关于nil的错误

1 个答案: