控制器創建動作中沒有方法錯誤

我已經閱讀了一些Q &至於在搜索這方面的一些幫助，但迄今尚未解決我的問題。我試圖自學ruby/rails，並且作爲一個測試項目，我想創建一個tvshows列表和一個字符列表，其中每個tvshow has_many字符以及每個字符屬於特定的節目。我確信我正在做一些基本的錯誤。任何援助將不勝感激。控制器創建動作中沒有方法錯誤

這裏是人物控制器：

class CharactersController < ApplicationController 
    before_action :set_character, only: [:show, :edit, :update, :destroy] 

    # GET /characters 
    # GET /characters.json 
    def index 
    @characters = Character.all 
    end 

    # GET /characters/1 
    # GET /characters/1.json 
    def show 
    end 

    # GET /characters/new 
    def new 
    @character = Character.new 
    end 

    # GET /characters/1/edit 
    def edit 
    end 

    # POST /characters 
    # POST /characters.json 
    def create 
    @character = @tvshow.characters.create(params[:character]) 

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

    # PATCH/PUT /characters/1 
    # PATCH/PUT /characters/1.json 
    def update 
    respond_to do |format| 
     if @character.update(character_params) 
     format.html { redirect_to @character, notice: 'Character was successfully updated.' } 
     format.json { head :no_content } 
     else 
     format.html { render action: 'edit' } 
     format.json { render json: @character.errors, status: :unprocessable_entity } 
     end 
    end 
    end 

    # DELETE /characters/1 
    # DELETE /characters/1.json 
    def destroy 
    @character.destroy 
    respond_to do |format| 
     format.html { redirect_to characters_url } 
     format.json { head :no_content } 
    end 
    end 

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

    # Never trust parameters from the scary internet, only allow the white list through. 
    def character_params 
     params.require(:character).permit(:first_name, :last_name, :bio) 
    end 
end

人物模型：

class Character < ActiveRecord::Base 
belongs_to :tvshow 
default_scope -> { order('created_at DESC') } 
validates :tvshow_id, presence: true 
end

tvshow模式：當我試圖創建一個角色得到返回

class Tvshow < ActiveRecord::Base 
has_many :characters, dependent: :destroy 
end

錯誤。這裏是完整的跟蹤：

app/controllers/characters_controller.rb:27:in `create' 
actionpack (4.0.0) lib/action_controller/metal/implicit_render.rb:4:in `send_action' 
actionpack (4.0.0) lib/abstract_controller/base.rb:189:in `process_action' 
actionpack (4.0.0) lib/action_controller/metal/rendering.rb:10:in `process_action' 
actionpack (4.0.0) lib/abstract_controller/callbacks.rb:18:in `block in process_action' 
activesupport (4.0.0) lib/active_support/callbacks.rb:413:in  `_run__1211653665462320621__process_action__callbacks' 
activesupport (4.0.0) lib/active_support/callbacks.rb:80:in `run_callbacks' 
actionpack (4.0.0) lib/abstract_controller/callbacks.rb:17:in `process_action' 
actionpack (4.0.0) lib/action_controller/metal/rescue.rb:29:in `process_action' 
actionpack (4.0.0) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action' 
activesupport (4.0.0) lib/active_support/notifications.rb:159:in `block in instrument' 
activesupport (4.0.0) lib/active_support/notifications/instrumenter.rb:20:in `instrument' 
activesupport (4.0.0) lib/active_support/notifications.rb:159:in `instrument' 
actionpack (4.0.0) lib/action_controller/metal/instrumentation.rb:30:in `process_action' 
actionpack (4.0.0) lib/action_controller/metal/params_wrapper.rb:245:in `process_action' 
activerecord (4.0.0) lib/active_record/railties/controller_runtime.rb:18:in `process_action' 
actionpack (4.0.0) lib/abstract_controller/base.rb:136:in `process' 
actionpack (4.0.0) lib/abstract_controller/rendering.rb:44:in `process' 
actionpack (4.0.0) lib/action_controller/metal.rb:195:in `dispatch' 
actionpack (4.0.0) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch' 
actionpack (4.0.0) lib/action_controller/metal.rb:231:in `block in action' 
actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:80:in `call' 
actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:80:in `dispatch' 
actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:48:in `call' 
actionpack (4.0.0) lib/action_dispatch/journey/router.rb:71:in `block in call' 
actionpack (4.0.0) lib/action_dispatch/journey/router.rb:59:in `each' 
actionpack (4.0.0) lib/action_dispatch/journey/router.rb:59:in `call' 
actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:655:in `call' 
rack (1.5.2) lib/rack/etag.rb:23:in `call' 
rack (1.5.2) lib/rack/conditionalget.rb:35:in `call' 
rack (1.5.2) lib/rack/head.rb:11:in `call' 
actionpack (4.0.0) lib/action_dispatch/middleware/params_parser.rb:27:in `call' 
actionpack (4.0.0) lib/action_dispatch/middleware/flash.rb:241:in `call' 
rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context' 
rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call' 
actionpack (4.0.0) lib/action_dispatch/middleware/cookies.rb:486:in `call' 
activerecord (4.0.0) lib/active_record/query_cache.rb:36:in `call' 
activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:626:in `call' 
activerecord (4.0.0) lib/active_record/migration.rb:369:in `call' 
actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call' 
activesupport (4.0.0) lib/active_support/callbacks.rb:373:in  `_run__2792846465963916895__call__callbacks' 
activesupport (4.0.0) lib/active_support/callbacks.rb:80:in `run_callbacks' 
actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call' 
actionpack (4.0.0) lib/action_dispatch/middleware/reloader.rb:64:in `call' 
actionpack (4.0.0) lib/action_dispatch/middleware/remote_ip.rb:76:in `call' 
actionpack (4.0.0) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call' 
actionpack (4.0.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call' 
railties (4.0.0) lib/rails/rack/logger.rb:38:in `call_app' 
railties (4.0.0) lib/rails/rack/logger.rb:21:in `block in call' 
activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `block in tagged' 
activesupport (4.0.0) lib/active_support/tagged_logging.rb:25:in `tagged' 
activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `tagged' 
railties (4.0.0) lib/rails/rack/logger.rb:21:in `call' 
actionpack (4.0.0) lib/action_dispatch/middleware/request_id.rb:21:in `call' 
rack (1.5.2) lib/rack/methodoverride.rb:21:in `call' 
rack (1.5.2) lib/rack/runtime.rb:17:in `call' 
activesupport (4.0.0) lib/active_support/cache/strategy/local_cache.rb:83:in `call' 
rack (1.5.2) lib/rack/lock.rb:17:in `call' 
actionpack (4.0.0) lib/action_dispatch/middleware/static.rb:64:in `call' 
railties (4.0.0) lib/rails/engine.rb:511:in `call' 
railties (4.0.0) lib/rails/application.rb:97:in `call' 
rack (1.5.2) lib/rack/lock.rb:17:in `call' 
rack (1.5.2) lib/rack/content_length.rb:14:in `call' 
rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service' 
/Users/dariusgoore/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service' 
/Users/dariusgoore/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run' 
/Users/dariusgoore/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/server.rb:191:in `block in  start_thread'

來源

2013-10-20 user2799827

錯誤中輸出的第一行是什麼？ youv'e向我們顯示了堆棧跟蹤，但不是錯誤消息本身。 –

您可以檢查出我的嵌套屬性，例如即在Nested Attributes example

我認爲下面的代碼將^ h elp你。

def new 
    @tvshow = Tvshow.find() # requires Tv show id in params so you can pass it in find block 
    @character = @tvshow.characters.build 
end 

def create 
    @character = Character.new(character_params) 

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

來源

2013-10-21 07:45:17

我的猜測是，你沒有設定＃創建行動CharactersController的@tvshow變量，它在抱怨的「爲無未定義的方法大字：nilClass」因爲這一點。

來源

2013-10-21 03:28:41

在創建方法替換下面的行：

@character = @ tvshow.characters.create（PARAMS [：字符]）

與

@character = Character.new（character_params ）

來源

2013-10-21 03:50:36

由於某些原因，我無法發佈評論，因此我將此作爲答案。

我做了上面提出的修改，在字符控制器的新動作中添加（params [：id]）作爲tvshow.find的參數。

由於某些原因，params [：id]似乎沒有提供我需要的tvshow_id。我現在得到了以下錯誤消息：沒有ID 提取的源無法找到Tvshow（大約線＃17）：

15＃GET /字符/新 16高清新 17 @tvshow = Tvshow.find（ params [：id]）＃需要在參數中顯示電視節目ID，所以你可以在發現塊中傳遞它 18 @character = @ tvshow.characters.build 19 end

來源

2013-10-21 15:49:19 user2799827

控制器創建動作中沒有方法錯誤

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