NoMethodError（未定義方法'posts'爲nil：NilClass）：app/controllers/posts_controller.rb：44：在`set_post'

Question

我正在爲一個燼博客項目構建一個rails後端。我正在通過rails驗證用戶操作，因此人們無法刪除他們未發佈的內容。使用我目前的設置，當我刪除時，出現標題中顯示的錯誤。 我已經包括了post控制器，它繼承的openreadcontroller，posts，comments和users的模型，因爲它們之間的關係可能會使「current_user」成爲一個零值，並且我包含了schema，因爲總有一個我貽誤了一次移民或其他事情。 我懷疑在執行銷燬方法時，我無法識別用戶。我有一個before操作，將@posts設置爲current_user.posts，這是發生錯誤的地方。如果確實是這個問題，我該如何確定current_user？ 在此先感謝您的幫助！

class PostsController < OpenReadController 
    before_action :set_post, only: [:show, :update, :destroy] 
    before_action :authenticate, only: [:create, :update, :destroy] 

    # GET /posts 
    def index 
    @posts = Post.all 

    render json: { posts: Post.all, comments: Comment.all } 
    end 

    # GET /posts/1 
    def show 
    render json: { post: @post, comments: @post.comments } 
    end 

    # POST /posts 
    def create 
    @post = current_user.posts.build(post_params) 
    if @post.save 
     render json: { post: @post, comments: @post.comments }, methods: :comment_ids, status: :created, location: @post 
    else 
     render json: @post.errors, status: :unprocessable_entity 
    end 
    end 

    # PATCH/PUT /posts/1 
    def update 
    if @post.update(post_params) 
     render json: @post 
    else 
     render json: @post.errors, status: :unprocessable_entity 
    end 
    end 

    # DELETE /posts/1 
    def destroy 
    @post.destroy 
    end 

    private 
    # Use callbacks to share common setup or constraints between actions. 
    def set_post 
     @post = current_user.posts.find(params[:id]) 
    end 

    # Only allow a trusted parameter "white list" through. 
    def post_params 
     params.require(:post).permit(:title, :body) 
    end 
end 

```

# frozen_string_literal: true 
# Inherit from this class to allow unauthenticate access to read actions 
class OpenReadController < ProtectedController 
    READ_ACTIONS = [:index, :show].freeze 
    skip_before_action :authenticate, only: READ_ACTIONS 
    before_action :set_current_user, only: READ_ACTIONS 
end 

```

class Post < ApplicationRecord 
    has_many :comments, dependent: :destroy 
    belongs_to :user 
end 

```

# frozen_string_literal: true 
class User < ApplicationRecord 
    include Authentication 
    has_many :posts 
    has_many :comments, through: :posts 
end 

```

class Comment < ApplicationRecord 
    belongs_to :post 
end 

```

ActiveRecord::Schema.define(version: 20170616000945) do 

    # These are extensions that must be enabled in order to support this database 
    enable_extension "plpgsql" 

    create_table "comments", force: :cascade do |t| 
    t.string "author" 
    t.text  "body" 
    t.integer "post_id" 
    t.datetime "created_at", null: false 
    t.datetime "updated_at", null: false 
    t.index ["post_id"], name: "index_comments_on_post_id", using: :btree 
    end 

    create_table "examples", force: :cascade do |t| 
    t.text  "text",  null: false 
    t.integer "user_id", null: false 
    t.datetime "created_at", null: false 
    t.datetime "updated_at", null: false 
    t.index ["user_id"], name: "index_examples_on_user_id", using: :btree 
    end 

    create_table "posts", force: :cascade do |t| 
    t.string "title" 
    t.text  "body" 
    t.datetime "created_at", null: false 
    t.datetime "updated_at", null: false 
    t.integer "user_id" 
    t.index ["user_id"], name: "index_posts_on_user_id", using: :btree 
    end 

    create_table "user_coins", force: :cascade do |t| 
    t.string "name" 
    t.decimal "price" 
    t.integer "user_id" 
    t.datetime "created_at", null: false 
    t.datetime "updated_at", null: false 
    t.index ["user_id"], name: "index_user_coins_on_user_id", using: :btree 
    end 

    create_table "users", force: :cascade do |t| 
    t.string "email",   null: false 
    t.string "token",   null: false 
    t.string "password_digest", null: false 
    t.datetime "created_at",  null: false 
    t.datetime "updated_at",  null: false 
    t.index ["email"], name: "index_users_on_email", unique: true, using: :btree 
    t.index ["token"], name: "index_users_on_token", unique: true, using: :btree 
    end 

    add_foreign_key "comments", "posts" 
    add_foreign_key "examples", "users" 
    add_foreign_key "posts", "users" 
    add_foreign_key "user_coins", "users" 
end 

``` 這裏是鉻控制檯數據，但我不知道它是有用的。

ember.debug.js:16905 Ember Data Request DELETE 
http://localhost:4741/posts/32 returned a 500 
Payload (application/json; charset=utf-8) 
[object Object] 
Error 
    at ErrorClass.AdapterError (http://localhost:7165/assets/vendor.js:88496:16) 
    at ErrorClass (http://localhost:7165/assets/vendor.js:88521:24) 
    at Class.handleResponse (http://localhost:7165/assets/vendor.js:89804:22) 
    at Class.handleResponse (http://localhost:7165/assets/vendor.js:73690:28) 
    at Class.superWrapper [as handleResponse] (http://localhost:7165/assets/vendor.js:50205:22) 
    at ajaxError (http://localhost:7165/assets/vendor.js:90169:25) 
    at Class.hash.error (http://localhost:7165/assets/vendor.js:89838:23) 
    at fire (http://localhost:7165/assets/vendor.js:3632:31) 
    at Object.fireWith [as rejectWith] (http://localhost:7165/assets/vendor.js:3762:7) 
    at done (http://localhost:7165/assets/vendor.js:9589:14) 

```

這裏的好辦法是我的服務器日誌。

Started DELETE "/posts/32" for 127.0.0.1 at 2017-06-17 00:57:01 -0400 
Processing by PostsController#destroy as HTML 
    Parameters: {"id"=>"32"} 
Completed 500 Internal Server Error in 3ms (ActiveRecord: 0.0ms) 



NoMethodError (undefined method `posts' for nil:NilClass): 

app/controllers/posts_controller.rb:44:in `set_post' 

在set_post方法

Answer 1

CURRENT_USER爲零。您不在OpenReadController中設置用於銷燬操作的current_user。所以請嘗試更改before_action :set_current_user, only: READ_ACTIONS至before_action :set_current_user, except: READ_ACTIONS。

# frozen_string_literal: true 
# Inherit from this class to allow unauthenticate access to read actions 
class OpenReadController < ProtectedController 
    READ_ACTIONS = [:index, :show].freeze 
    skip_before_action :authenticate, only: READ_ACTIONS 
    before_action :set_current_user, except: READ_ACTIONS 
end