Ruby rails：如何在不刷新页面的情况下 post 发表评论？

Question

我正在尝试使用 rails 6 和 jQuery 实现评论功能，但我希望用户可以向 posts 添加评论在不刷新浏览器的情况下，我创建了一个 comment_controller.rb 和模型 comment.rb,
然后我通过has_many: comments关联post和用户和评论模型，并且属于用户和post，但问题是当我我正在尝试创建一个 post 我发现了这个错误：

app/controllers/comments_controller.rb:8:in `create'
Started POST "/comments" for ::1 at 2021-06-10 09:56:42 +0200
Processing by CommentsController#create as JS
  Parameters: {"comment"=>{"user_id"=>"1", "body"=>"good one ;)"}, "commit"=>"Post"}
   (3.8ms)  SELECT sqlite_version(*)
  User Load (15.0ms)  SELECT "users".* FROM "users" WHERE "users"."id" = ? ORDER BY "users"."id" ASC LIMIT ?  [["id", 1], ["LIMIT", 1]]
  TRANSACTION (0.1ms)  begin transaction
  ↳ app/controllers/comments_controller.rb:11:in `create'
  User Load (0.5ms)  SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT ?  [["id", 1], ["LIMIT", 1]]
  ↳ app/controllers/comments_controller.rb:11:in `create'
  TRANSACTION (0.1ms)  rollback transaction
  ↳ app/controllers/comments_controller.rb:11:in `create'
  Rendering comments/create.js.erb
  Rendered comments/create.js.erb (Duration: 294.2ms | Allocations: 1386)
Completed 500 Internal Server Error in 7130ms (ActiveRecord: 105.2ms | Allocations: 21119)

ActionView::Template::Error (undefined method `comments' for nil:NilClass):
    1:
    2: $('#comment_pane').append("<%= j render @post.comments.last %>");
    3: $('#comment_body').val('');

app/views/comments/create.js.erb:2

这是我的comment_controller.rb:

class CommentsController < ApplicationController
    before_action :authenticate_user!
    def create  
        @comment = Comment.new(comment_params)
        @comment.user_id = current_user.id if user_signed_in?
        @comment.save           
    end
    def destroy 
        @comment.destroy  
    end
    private
    def comment_params
      params.require(:comment).permit(:body, :user_id, :post_id)
    end
end

这是我的评论行 index.html.erb :

<div id="comment_pane" class=" comment-box " >
   <%= render "comments/comments", post: post %>
</div>

<div class="bottom border-t pt-3 mt-3">
   <%= render  'comments/form' %>
</div>

这个_form.html.erb:

<%= form_for Comment.new, remote: true  do |f| %>
    <%= f.hidden_field :user_id, value: current_user.id %>

    <%= f.text_field :body, placeholder: "add comment here ..." %>
    <%= f.submit "Post", class: "comment-button text-blue-500 opacity-75 w-2/12 text-center font-bold", autocomplete: :off %>
<% end %>

create.js.erb :

$('#comment_pane').append("<%= j render @post.comments.last %>");
$('#comment_body').val('');

我面临的问题是，在用户提交评论后我发现了这个错误：

undefined method `comments' for nil:NilClass  
app/views/comments/create.js.erb:2

有什么帮助吗？

Answer 1

您收到错误是因为您的视图期望 @post 存在但未定义。您可以修改 CommentsController#create 以包含创建的评论的 post.

class CommentsController < ApplicationController
    def create  
        @comment = Comment.new(comment_params)
        @comment.user_id = current_user.id if user_signed_in?
        @comment.save
        @post = @comment.post # or Post.find(comment_params[:post_id])
    end
end

Ruby rails：如何在不刷新页面的情况下 post 发表评论？

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