如何以及在哪里处理相关记录的更新过程？ [英] How and where to handle the updating process of associated records?

问题描述

我在使用Ruby on Rails 4，我想通过 update_attributes的的方法，妥善处理更新和创造相关记录过程。也就是说，我有以下几点：

I am using Ruby on Rails 4 and I would like to properly handle the updating and creating process of associated records through the update_attributes method. That is, I have the following:

# Model
class Article < ActiveRecord::Base
  has_many :categories

  accepts_nested_attributes_for :categories
end

# Controller
class ArticlesController < ApplicationController
  def update
    @article = Article.find(params[:id])

    @article.update_attributes(update_params)
    ...
  end

  private

  def update_params
    params.require(:article).permit(:title, ..., :categories_attributes => [:name, ...])
  end
end

# Logger for the update request
Started PATCH "/articles/6"
Processing by ArticlesController#update
  Parameters: {"utf8"=>"✓", "article"=>{"title"=>"Sample title", "categories_attributes"=>{"0"=>{"name"=>"Sample Category 1", "..."=>"..."}, "1"=>{"name"=>"Sample Category 2", "..."=>"..."}, : "..." => {...}}
  ...

这个问题是关系到Rails的方式处理事情在数据库中更新通过 @article 对象类别时，更新相关记录，在我的情况：当数据被提交所以火更新操作和参数传递给 update_attributes的方法（如上面的记录器），然后滑轨创建新的类别记录在数据库中，每一个元素present中的散列 categories_attributes 。

The issue is related to the way Rails handles things for updating associated records in the database, in my case when updating categories through the @article object: when data is submitted so to fire the update action and parameters are passed to the update_attributes method (as shown in the logger above) then Rails creates new category records in the database, one for each element present in the hash categories_attributes.

然而，的我的意思是，如果这些存在更新现有的类别记录或创建新的，如果这些不存在的，相应的的article_id 和名称在类别列数据库表，probabily执行搜索数据present在这些列为了判断是否需要更新或创建新的记录。事实上，在编辑文章的观点我显示与编辑类别，包括字段输入字段的表单pre-填充与现有的类别和空字段可以创建对飞类别的数据由编辑用户。

However, my intention is to update existing category records if those exist or create new ones if those do not exist, accordingly to the uniqueness of article_id and name columns in the categories database table, probabily performing a search for data present in these columns in order to check if it is needed to update or create new records. In fact, in the "edit article" view I display a form with input fields for editing categories including fields pre-populated with data related to existing categories and empty fields for categories that can be created "on the fly" by the editor user.

我如何妥善处理这一问题？难道模型或控制器的责任？或者，也许，有没有更好的方式来直接在编辑文章视图管理类别？

How can I properly handle this behavior? Is it model or controller responsability? Or, maybe, is there a better way to manage categories directly in the "edit article" view?

推荐答案

您应该添加 categories_attributes 为 attr_accessible 的你的文章模式。像：

You should add categories_attributes as attr_accessible in your Article model. Like:

attr_accessible :categories_attributes

如果没有这一行，你一定要面对像上述问题，创造新的记录，而不是更新现有的。另外有一个叫宝石 nested_form 它做了出色的工作在建设这些复杂的形式。

Without this line you are bound to face issues like above, creating new records instead of updating existing ones. Also there is a gem called nested_form which does an excellent job in building these complex forms.

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