Question

我知道有很多类似的帖子，人们有同样的问题，但没有一个帮助我。如果我创建新文章，那么它将没有类别。但是，如果我编辑之前在seed.rb中创建的文章，则更新类别。怎么了？

分类表：

class CreateCategories < ActiveRecord::Migration
  def change
    create_table :categories do |t|
      t.string :name
      t.timestamps
    end
  end
end

category.rb

class Category < ActiveRecord::Base
    has_many :articles
end

article.rb

class Article < ActiveRecord::Base
   belongs_to :category
end

然后我有一个_form文件

<%= form_for(@article) do |f| %>

  <div class="title">
        <%= f.label :title %>
        <%= f.text_field :title %>
  </div>
  <div class="content">
        <%= f.label :content %>
        <%= f.text_field :content %>
  </div>
  <div class="category">
        <%= f.label :category %>
        <%= collection_select(:article, :category_id, Category.all, :id, :name) %>
  </div>
  <div class="actions">
        <%= f.submit %>
  </div>
<% end %>

有一个categories_controller文件：

class CategoriesController < ApplicationController
  def index
    @categories = Category.all
  end

  def show
    @category = Category.find(params[:id])
    @articles = @category.articles
  end

  def new
    @category = Category.new
  end

  def create
    @category = Category.new(category_params)
    if @category.save
      redirect_to(:action => 'index')
    else
      render('new')
    end
  end

  def edit
    @category = Category.find(params[:id])
  end

  def update
    @category = Category.find(params[:id])
    if @category.update_attributes(category_params)
      redirect_to(:action => 'show', :id => @category.id)
    else
      render('index')
    end
  end

  def delete
    @category = Category.find(params[:id])
  end

  def destroy
    Category.find(params[:id]).destroy
    redirect_to(:action => 'index')
  end

  private

  def category_params
    params.require(:category).permit(:name)
  end
end

文章控制器文件：

class ArticlesController < ApplicationController
  def index
    @articles = Article.all
  end

  def show
        @article = Article.find(params[:id])
  end

  def new
        @article = Article.new
  end

  def create
    @article = Article.new(article_params)
    if @article.save
        redirect_to(:action => 'index')
    else
        render('new')
    end
  end

  def edit
    @article = Article.find(params[:id])
  end

  def update
    @article = Article.find(params[:id])
    if @article.update_attributes(article_params)
        redirect_to(:action => 'show', :id => @article.id)
    else
        render('index')
    end
  end

  def delete
    @article = Article.find(params[:id])
  end

  def destroy
    Article.find(params[:id]).destroy
    redirect_to(:action => 'index')
  end

  private
  def article_params
    params.require(:article).permit(:title, :content)
  end
end

Answer 1

您似乎未在articles#create操作中构建关联。 category_id是通过您的表单发送的，但您仍需要构建Active Record关联。您可以在文章控制器中尝试这样的事情：

def create
    @article = Article.new(article_params)
    @category = Category.find(params[:category_id])
    @article.category = @category
    if @article.save
        redirect_to(:action => 'index')
    else
        render('new')
    end
  end

请注意，有多种方法可以创建关联。您的文章类具有以下five methods来操纵关联：

@article.category  
@article.category= 
@article.build_category 
@article.create_category
@article.create_category!

collection_select不会通过表单保存

1 个答案: