删除赋值，未定义的方法`avatar？'为零：NilClass

I am a new student to Ruby on Rails and am currently working on the Deletion HTTP request for my project, a Reddit clone. So far I have implemented Destroy functionality on Topics and Posts successfully. Now that I am working on the deletion of Comments I have hit an error that I am not sure how to deal with.

我是Ruby on Rails的新生,目前我正在为我的项目删除HTTP请求,一个Reddit克隆。到目前为止,我已经成功地在主题和帖子上实现了Destroy功能。现在我正在努力删除评论,我遇到了一个错误,我不知道如何处理。

Here was the instruction.

这是指令。

Finally, we also have to modify the comment-listing view -- the app/views/comments/_comment.html.erb partial called in posts#show. Update the partial to look this:

最后,我们还必须修改评论列表视图 - 在帖子#show中调用的app / views / comments / _comment.html.erb部分。更新部分看看:

<div class="media">
  <div class="media-left">
    <%= image_tag(comment.user.avatar.small.url, class: "media-object") if comment.user.avatar? %>
  </div>
  <div class="media-body">
    <small>
      <%= comment.user.name %> commented <%= time_ago_in_words(comment.created_at) %> ago
      <% if policy(comment).destroy? %>
        | <%= link_to "Delete", [@topic, @post, comment], method: :delete %>
      <% end %>
    </small>
    <p><%= comment.body %></p>
  </div>
</div>

My _comment.html.erb before the change:

我改变之前的_comment.html.erb:

<% @comments.each do |comment| %>

  <p><%= comment.body %></p>
  <p><i><%= comment.user.name %></i></p>

<% end %>

After modifying the code as instructed I receive this error:

按照指示修改代码后,我收到此错误:

NoMethodError at /topics/4/posts/11 undefined method `avatar?' for nil:NilClass

NoMethodError at / topics / 4 / posts / 11 undefined method`avatar?'为零:NilClass

With this line highlighted:

突出显示此行:

<%= image_tag(comment.user.avatar.small.url, class: "media-object") if comment.user.avatar? %>

Here is my views/post/show.html.erb:

这是我的观点/帖子/ show.html.erb:

<h1><%= markdown_to_html @post.title %></h1>

<div class="row">
  <div class="col-md-8">
    <small>
      <%= image_tag(@post.user.avatar.tiny.url) if @post.user.avatar? %>
      submitted <%= time_ago_in_words(@post.created_at) %> ago by
      <%= @post.user.name %>
    </small>
    <p><%= markdown_to_html @post.body %></p>
    <p><%= image_tag(@post.image.post.url) if @post.image? %>

    <h1>Comments</h1>
    <!-- render the comments loop -->
    <%= render partial: 'comments/comment', locals: { topic: @topic, post: @post, comment: @comment } %>

    <!-- render the comments form if user is signed in -->
    <% if policy(@comment).create? %>
      <%= render partial: 'comments/form', locals: { topic: @topic, post: @post, comment: @comment } %>
    <% end %>

  </div>
  <div class="col-md-4">
    <% if policy(@post).edit? %>
      <%= link_to "Edit", edit_topic_post_path(@topic, @post), class: 'btn btn-success' %>
    <% end %>
    <% if policy(@post).destroy? %>
      <%= link_to "Delete Post", [@topic, @post], method: :delete, class: 'btn btn-danger', data: { confirm: 'Are you sure you want to delete this post?' } %>
    <% end %>
  </div>
</div>

comments controller

class CommentsController < ApplicationController
  def create
    # find topic by id
    @topic = Topic.find(params[:topic_id])
    # find post id through topic
    @post = @topic.posts.find(params[:post_id])
    # comments on post
    @comments = @post.comments

    @comment = current_user.comments.build(params.require(:comment).permit(:body, :post_id, :avatar))
    @comment.post = @post


    authorize @comment
    if @comment.save
      flash[:notice] = "Comment was created."
      redirect_to [@topic, @post]
    else
      flash[:error] = "Error saving the comment. Please try again."
      # must render the the page calling the form!!
      render 'posts/show'
    end
  end

  def new

  end

  def destroy
    @topic = Topic.find(params[:topic_id])
    @post = Post.posts.find(params[:post_id])
    @comment = @post.comments.find(params[:id])

    authorize @comment
    if @comment.destroy
      flash[:notice] = "Comment was removed."
      redirect_to [@topic, @post]
    else
      flash[:error] = "Comment couldn't be deleted. Try again."
      redirect_to [@topic, @post]
    end
  end
end

user model

class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable, :confirmable
  has_many :posts
  has_many :comments

  # CarrierWave method for attribute functionality
  mount_uploader :avatar, AvatarUploader

  # These methods check the role of a user in the database
  def admin?
    role == 'admin'
  end

  def moderator?
    role == 'moderator'
  end
end

I have attempted to change my comment.user.avatar.small.url to @comment.user.avatar.small.url based off how the rest of my images were handled in the project. The error still persists.

我试图根据项目中其余图像的处理方式将我的comment.user.avatar.small.url更改为@ comment.user.avatar.small.url。错误仍然存在。

Best regards.

1 个解决方案

#1

This is error means that comment.user is nil. If you want to fix it you should investigate why this happens.

这是错误意味着comment.user是nil。如果你想修复它,你应该调查为什么会发生这种情况。

If this is the correct case (for example this is an anonymous user) then you can handle it use something like:

如果这是正确的情况(例如,这是一个匿名用户),那么您可以使用以下内容处理它:

... if comment.user.try(:avatar?)

#1