显示 nil：NilClass 的未定义方法"帖子"的关联

Question

我的rails应用程序中有3个模型，我正在尝试将它们与关联

我用设备创建的用户模型

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_one :userdetail
  has_many :posts
  has_many :topics, :through => :posts
end

这是我的主题模型

class Topic < ActiveRecord::Base
  #relation between topics and post
  has_many :posts
end

这是我的后模型

class Post < ActiveRecord::Base
  #relation between topics and post
  belongs_to :topic
  belongs_to :user
  #post is valid only if it's associated with a topic:
   validates :topic_id, :presence => true
  #can also require that the referenced topic itself be valid
  #in order for the post to be valid:
  validates_associated :topic
end

这是我的后控制器

class PostsController < ApplicationController
 # before_action :set_post, only: [:show, :edit, :update, :destroy]
  before_filter :has_userdetail_and_topic, :only =>[:new, :create]
  # GET /posts
  # GET /posts.json
  #for new association SAAS book
  protected
  def has_userdetail_and_topic
    unless(@topic =Topic.find_by_id(params[:topic_id]))
      flash[:warning] = 'post must be for an existing topic'
    end
  end
  public
  def new
    @post = @topic.posts.build
    #@@topic = Topic.find(params[:topic_id1])
  end
  def index
    @posts = Post.all
  end
  # GET /posts/1
  # GET /posts/1.json
  def show
  end
  # GET /posts/new
  # GET /posts/1/edit
  def edit
  end
  # POST /posts
  # POST /posts.json
  def create
    @current_user.posts << @topic.posts.build(params[:post])
    #@topic.posts << @post
    #@post = Post.new(post_params )
    #@post.userdetail_id = current_user.id
     #Association functional between topic and post
     #Class variable used
     #@@topic.posts << @post
    respond_to do |format|
      if @post.save
        format.html { redirect_to @post, notice: 'Post was successfully created.' }
        format.json { render :show, status: :created, location: @post }
      else
        format.html { render :new }
        format.json { render json: @post.errors, status: :unprocessable_entity }
      end
    end
  end
  # PATCH/PUT /posts/1
  # PATCH/PUT /posts/1.json
  def update
    respond_to do |format|
      if @post.update(post_params)
        format.html { redirect_to @post, notice: 'Post was successfully updated.' }
        format.json { render :show, status: :ok, location: @post }
      else
        format.html { render :edit }
        format.json { render json: @post.errors, status: :unprocessable_entity }
      end
    end
  end
  # DELETE /posts/1
  # DELETE /posts/1.json
  def destroy
    @post.destroy
    respond_to do |format|
      format.html { redirect_to posts_url, notice: 'Post was successfully destroyed.' }
      format.json { head :no_content }
    end
  end
  private
    # Use callbacks to share common setup or constraints between actions.
    def set_post
      @post = Post.find(params[:id])
    end
    # Never trust parameters from the scary internet, only allow the white list through.
    def post_params
      params.require(:post).permit(:topic_id,:issue, :description, :rating, :user_id)
    end
end

这是我发布的新视图

<%= form_tag topic_posts_path(@topic) do  %>
    <%= label :post, :description %>
<%= text_area :post, :description %>
    <%= submit_tag 'Create post' %>
<%end%>

我在后控制器中得到了这个错误。我不确定为什么我会得到这个错误

nil的未定义方法"posts"：@current_user.posts<的NilClass<topic.posts.build（params[：post]）

我正在尝试将主题和帖子关联起来在我的专题节目中。

我使用了代码<%=link_to"写入"，new_topic_post_path（topic_id:@topic）%>

<%= link_to 'Write', new_topic_post_path(topic_id: @topic) %>

我正在使用设备进行用户登录，但我没有在应用程序中的任何位置设置current_user。

我想创建一个应用程序，用户可以在其中创建关于主题的帖子。每个主题都有多个帖子。我是新来的，正在学习RoR，所以请解释答案

Answer 1

设备为您提供current_user助手（无@）。使用它，而不是@current_user。

您可能还想设置

before_filter :authenticate_user

在你的帖子PostsController中-确保current_user不是nil（并且用户正确登录）。

创建方法的一部分也应该更改：

@post = @topic.posts.build(post_params)
@current_user.posts << @post