Rails 评论和用户名不会显示在帖子视图中/未定义的方法"用户"为 nil：NilClass

Question

所以我有一个post.rb模型，我可以在其中显示谁在节目的文章视图中写下帖子，而且效果很好。

但是，我一直在尝试添加属于帖子的评论，也属于用户。

我似乎无法获取所有评论或发布coments以显示在帖子Show.html.erb的用户的名称。

我想我的问题是，如何在控制器和模型视图之间集成控制器和模型信息？我知道它是否存在于模型和控制器中，以及相同类型的视图，它是可访问的，但是交联或共享控制器模型信息对我来说很难。

我希望能够显示发表评论的用户，以及帖子的表演视图中的评论正文，而不是评论。

comment.rb

class Comment < ApplicationRecord
  belongs_to :post
  belongs_to :user
  validates :body, :presence => true
end

post.rb

class Post < ApplicationRecord
  belongs_to :user, optional: true
  validates :user, presence: true;
  validates :title, presence: true,
                    length: { minimum: 5}

  extend FriendlyId
  friendly_id :title, use: :slugged
  validates :title, :slug, presence: true
  # comments
  has_many :comments
end

user.rb

class User < ApplicationRecord
  has_many :posts, dependent: :destroy
  has_many :comments, dependent: :destroy
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable
  validates :first_name, presence: true
  validates :last_name, presence: true
  validates :school_name, presence: true, inclusion: { in: %w(Harvard Yale),
    message: "%{value} is not a valid choice" }
  validates :graduation_year, presence: true, inclusion: { in: %w(2017 2018 2019 2020 2021 2022 2023),
    message: "%{value} is not a valid choice currently" }
    def superadmin?
      self.role.name == "Superadmin"
    end 
end

comment_controller.rb

class CommentsController < ApplicationController
before_action :authenticate_user!
# GET /posts/:post_id/comments
# GET /posts/:post_id/comments.xml
def index
#1st you retrieve the post thanks to params[:post_id]
post = Post.friendly.find(params[:post_id])
#2nd you get all the comments of this post
@comments = post.comments
respond_to do |format|
  format.html # index.html.erb
  format.xml  { render :xml => @comments }
end
 end
 # GET /posts/:post_id/comments/:id
 # GET /comments/:id.xml
 def show
 #1st you retrieve the post thanks to params[:post_id]
 post = Post.friendly.find(params[:post_id])
 #2nd you retrieve the comment thanks to params[:id]
 @comment = post.comments.find(params[:id])
respond_to do |format|
  format.html # show.html.erb
  format.xml  { render :xml => @comment }
end
end
# GET /posts/:post_id/comments/new
# GET /posts/:post_id/comments/new.xml
def new
#1st you retrieve the post thanks to params[:post_id]
post = Post.friendly.find(params[:post_id])
#2nd you build a new one
@comment = post.comments.new(params[:comment])
@comment.user = current_user
end
# GET /posts/:post_id/comments/:id/edit
def edit
#1st you retrieve the post thanks to params[:post_id]
post = Post.friendly.find(params[:post_id])
#2nd you retrieve the comment thanks to params[:id]
@comment = post.comments.find(comment_params[:id])
end
# POST /posts/:post_id/comments
# POST /posts/:post_id/comments.xml
def create
#1st you retrieve the post thanks to params[:post_id]
post = Post.friendly.find(params[:post_id])
#2nd you create the comment with arguments in params[:comment]
@comment = post.comments.create(comment_params)
@comment.user = current_user

respond_to do |format|
  if @comment.save
    #1st argument of redirect_to is an array, in order to build the correct route to the nested resource comment
    format.html { redirect_to([@comment.post, @comment], :notice => 'Comment was successfully created.') }
    #the key :location is associated to an array in order to build the correct route to the nested resource comment
    format.xml  { render :xml => @comment, :status => :created, :location => [@comment.post, @comment] }
  else
    format.html { render :action => "new" }
    format.xml  { render :xml => @comment.errors, :status => :unprocessable_entity }
  end
end
end

Answer 1

在post_controller的show方法中，您需要执行以下操作：

def show 
  @post = Post.find_by(id: params[:id]) # or however you find your post
  ....
end

然后，在您的views/posts/_show.html.erb中（如果您使用ERB），您将执行类似：

的事情

<% @post.comments.each do |comment| %>
  ... show some comment stuff 
  <%= comment.user.name %>
<% end %>