Ruby on rails 事件中的命名错误#show |未定义的方法` firstname'；零级：零级

我对RubyonRails非常陌生，如果我下面的问题非常基本，我会提前道歉，如果有任何帮助，我将不胜感激

继“railscast#154多态关联”之后，我现在能够为活动和博客创建评论

但我想做的是，当用户发表评论时，用户（发表评论的用户）的名字会与他们发表的评论一起出现……如下所示

详细内容如下-在我的视图/comments/_comments.html.erb文件中，我在添加了@comments.user=current_user的索引方法中放置了&controllers/comments\u controller.rb，但无法让它显示当前_用户名和他们发布的注释，如下所示

艾玛·汤普森这是一个伟大的事件，非常享受

emma thompson是目前的_用户

大事，好好享受吧！作为评论

-问题：如何调用发表评论的用户的姓名？

错误消息

NoMethodError in Events#show
Showing /Users/ARTLoe/00_GitH/00_Projects/spefz_app/app/views/comments/_comments.html.erb where line #5 raised:
undefined method `firstname' for nil:NilClass

    <ul>
    <% @comments.each do |comment| %>
      <li>
        <%= comment.user.firstname %>          #<--------------error appears on this line
        <%= simple_format comment.content %>
      </li>
    <% end %>

型号

class Comment < ActiveRecord::Base
  belongs_to :commentable, polymorphic: true
  belongs_to :user
end

class Event < ActiveRecord::Base
  belongs_to :user
  has_many :comments, as: :commentable
end

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

#<<<COMMENT CONTROLLER
class CommentsController < ApplicationController
  before_action :set_comment, only: [:show, :edit, :update, :destroy]
  before_filter :load_commentable

  def index
    @comments = @commentable.comments
    @comments.user = current_user
  end

  def show
  end

  def new
    @comment = @commentable.comments.new
  end

  def edit
  end

  def create
    @comment = @commentable.comments.new(comment_params)

    respond_to do |format|
      if @comment.save
        format.html { redirect_to [@commentable], notice: 'Comment was successfully created.' }
        format.json { render :show, status: :created, location: @comment }
      else
        format.html { render :new }
        format.json { render json: @comment.errors, status: :unprocessable_entity }
      end
    end
  end

  def update
    respond_to do |format|
      if @comment.update(comment_params)
        format.html { redirect_to @comment, notice: 'Comment was successfully updated.' }
        format.json { render :show, status: :ok, location: @comment }
      else
        format.html { render :edit }
        format.json { render json: @comment.errors, status: :unprocessable_entity }
      end
    end
  end

  def destroy
    @comment.destroy
    respond_to do |format|
      format.html { redirect_to events_url, notice: 'Comment was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_comment
      @comment = Comment.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def comment_params
      params.require(:comment).permit(:content, :user_id)
    end

    def load_commentable
      resource, id = request.path.split('/')[1, 2]
      @commentable = resource.singularize.classify.constantize.find(id)
    end
end


#<<<EVENT CONTROLLER
class EventsController < ApplicationController
  before_action :set_event, only: [:show, :edit, :update, :destroy]
  before_filter :authenticate_user!

  def index
    @events = Event.order(:date)
    # @events = current_user.events | displays only events by current user
  end

  def show
    @commentable = @event
    @comments = @commentable.comments
    @comment = Comment.new
  end

  def new
    @event = Event.new
  end

  def edit
  end

  def create
    @event = Event.new(event_params)

    respond_to do |format|
      if @event.save
        format.html { redirect_to @event, notice: 'Event was successfully created.' }
        format.json { render :show, status: :created, location: @event }
      else
        format.html { render :new }
        format.json { render json: @event.errors, status: :unprocessable_entity }
      end
    end
  end

  def update
    respond_to do |format|
      if @event.update(event_params)
        format.html { redirect_to @event, notice: 'Event was successfully updated.' }
        format.json { render :show, status: :ok, location: @event }
      else
        format.html { render :edit }
        format.json { render json: @event.errors, status: :unprocessable_entity }
      end
    end
  end

  def destroy
    @event.destroy
    respond_to do |format|
      format.html { redirect_to events_url, notice: 'Event was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    def set_event
      @event = Event.find(params[:id])
    end

    def event_params
      params.require(:event).permit(:name, :description, :date, :time, :city, :price)
    end
end

class注释

控制器

class Comment < ActiveRecord::Base
  belongs_to :commentable, polymorphic: true
  belongs_to :user
end

class Event < ActiveRecord::Base
  belongs_to :user
  has_many :comments, as: :commentable
end

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

#<<<COMMENT CONTROLLER
class CommentsController < ApplicationController
  before_action :set_comment, only: [:show, :edit, :update, :destroy]
  before_filter :load_commentable

  def index
    @comments = @commentable.comments
    @comments.user = current_user
  end

  def show
  end

  def new
    @comment = @commentable.comments.new
  end

  def edit
  end

  def create
    @comment = @commentable.comments.new(comment_params)

    respond_to do |format|
      if @comment.save
        format.html { redirect_to [@commentable], notice: 'Comment was successfully created.' }
        format.json { render :show, status: :created, location: @comment }
      else
        format.html { render :new }
        format.json { render json: @comment.errors, status: :unprocessable_entity }
      end
    end
  end

  def update
    respond_to do |format|
      if @comment.update(comment_params)
        format.html { redirect_to @comment, notice: 'Comment was successfully updated.' }
        format.json { render :show, status: :ok, location: @comment }
      else
        format.html { render :edit }
        format.json { render json: @comment.errors, status: :unprocessable_entity }
      end
    end
  end

  def destroy
    @comment.destroy
    respond_to do |format|
      format.html { redirect_to events_url, notice: 'Comment was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_comment
      @comment = Comment.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def comment_params
      params.require(:comment).permit(:content, :user_id)
    end

    def load_commentable
      resource, id = request.path.split('/')[1, 2]
      @commentable = resource.singularize.classify.constantize.find(id)
    end
end


#<<<EVENT CONTROLLER
class EventsController < ApplicationController
  before_action :set_event, only: [:show, :edit, :update, :destroy]
  before_filter :authenticate_user!

  def index
    @events = Event.order(:date)
    # @events = current_user.events | displays only events by current user
  end

  def show
    @commentable = @event
    @comments = @commentable.comments
    @comment = Comment.new
  end

  def new
    @event = Event.new
  end

  def edit
  end

  def create
    @event = Event.new(event_params)

    respond_to do |format|
      if @event.save
        format.html { redirect_to @event, notice: 'Event was successfully created.' }
        format.json { render :show, status: :created, location: @event }
      else
        format.html { render :new }
        format.json { render json: @event.errors, status: :unprocessable_entity }
      end
    end
  end

  def update
    respond_to do |format|
      if @event.update(event_params)
        format.html { redirect_to @event, notice: 'Event was successfully updated.' }
        format.json { render :show, status: :ok, location: @event }
      else
        format.html { render :edit }
        format.json { render json: @event.errors, status: :unprocessable_entity }
      end
    end
  end

  def destroy
    @event.destroy
    respond_to do |format|
      format.html { redirect_to events_url, notice: 'Event was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    def set_event
      @event = Event.find(params[:id])
    end

    def event_params
      params.require(:event).permit(:name, :description, :date, :time, :city, :price)
    end
end

---

#你就快到了。如果您始终希望创建操作的用户是当前用户，则需要在创建操作中设置该用户

def create
  @comment = @commentable.comments.new(comment_params)
  @comment.user = current_user

  respond_to do |format|
    if @comment.save
      format.html { redirect_to [@commentable], notice: 'Comment was successfully created.' }
      format.json { render :show, status: :created, location: @comment }
    else
      format.html { render :new }
      format.json { render json: @comment.errors, status: :unprocessable_entity }
    end
  end
end

此外，您还需要删除索引操作上的
@comments.user=current\u user
。您希望以视图中已有的方式阅读它：
comment.user.firstname
，而不是在索引操作中写入它（实际上这不会做任何事情，因为@comments是注释列表的一个关系，您无论如何都不能将每个注释都设置为那样）
我很确定，在您的索引操作中，
@comments.user=current\u user
会给您一个错误。您在那里有一个活动记录集合，并且正在尝试为其设置一个值。一方面，索引操作不应该在模型上设置属性，另一方面，如果要设置值，则需要在每个单独的模型上设置。见@tehfailsafe的答案。