獲取「表單中的第一個參數不能包含零或爲空」錯誤

Question

第一次問一個問題並不確定我是否正確地做了這件事，但是在這裏。我收到此錯誤

在形式上不能包含零或爲空 /nameofapp/app/views/products/_form.html.erb

第一個參數，其中線＃1提出：

這裏有我的鏈接：

視圖

<%= form_for(@product) do |f| %> 
    <% if @product.errors.any? %> 
    <div id="error_explanation"> 

控制研究呃

class ProductsController < ApplicationController 
before_action :set_product, only: [:show, :edit, :update, :destroy] 

# GET /products 
# GET /products.json 
def index 
    @products = Product.all 
end 

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

# GET /products/new 
def new 
    @product = Product.new 
end 

# GET /products/1/edit 
def edit 
end 

# POST /products 
# POST /products.json 
def create 
    @product = Product.new(product_params) 

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

# PATCH/PUT /products/1 
# PATCH/PUT /products/1.json 
def update 
    respond_to do |format| 
    if @product.update(product_params) 
     format.html { redirect_to @product, notice: 'Product was successfully updated.' } 
     format.json { render :show, status: :ok, location: @product } 
    else 
     format.html { render :edit } 
     format.json { render json: @product.errors, status: :unprocessable_entity } 
    end 
    end 
end 

# DELETE /products/1 
# DELETE /products/1.json 
def destroy 
    @product.destroy 
    respond_to do |format| 
    format.html { redirect_to products_url, notice: 'Product was successfully destroyed.' } 
    format.json { head :no_content } 
    end 
end 

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

    # Never trust parameters from the scary internet, only allow the white list through. 
    def product_params 
    params.require(:product).permit(:name, :description, :image_url, :colour, :price) 
    end 

末 ＃PATCH/PUT /產品/ 1 ＃PATCH/PUT /products/1.json 高清更新 的respond_to做|格式| if @ product.update（product_params） format.html {redirect_to @product，notice：'Product was successfully updated。' } format.json {render：show，status：ok，location：@product else format.html {render：edit} format.json {render json：@ product.errors，status：：unprocessable_entity} 最終 結束 結束

# DELETE /products/1 
# DELETE /products/1.json 
def destroy 
    @product.destroy 
    respond_to do |format| 
    format.html { redirect_to products_url, notice: 'Product was successfully destroyed.' } 
    format.json { head :no_content } 
    end 
end 

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

    # Never trust parameters from the scary internet, only allow the white list through. 
    def product_params 
    params.require(:product).permit(:name, :description, :image_url, :colour, :price) 
    end 

末

Answer 1

如果我是正確的你渲染局部的index.html.erb，如果是更改控制器的index行動，以低於

def index 
    @products = Product.all 
    @product = Product.new 
end 

Answer 2

我覺得出具來自edit行動，它不具備@product值

它應該被更新爲這樣的東西

def edit 
    @product = Product.find(param[:id]) 
end 

Answer 3

@product是零，你必須加載它。

您必須在控制器中將其加載到所需的操作中。就像在編輯或顯示操作中一樣。

@product = Product.find(params[:id]) 

或確保在set_product中擁有它。

private 

def set_product 
    @product = Product.find(params[:id]) 
end