如何检查“has_many :through”关联中的复选框？答案

【问题标题】：How to check checkbox in the "has_many :through" association?如何检查“has_many :through”关联中的复选框？
【发布时间】：2013-10-29 10:04:58
【问题描述】：

我有这些模型：

class Category < ActiveRecord::Base  
  has_many :product_categories, :dependent => :destroy
  has_many :product, :through => :product_categories
end

class Product < ActiveRecord::Base 
  has_many :product_categories, :dependent => :destroy
  has_many :categories, :through => :product_categories
end

class ProductCategory < ActiveRecord::Base
  belongs_to :category
  belongs_to :product
end

观点：

- Category.order('title').each do |category|
  = check_box_tag :product_categories_ids, category.id, @product.product_categories.include?(category), :name => 'product[product_categories_ids][]'
  = label_tag :product_categories_ids, category.title

当我打印出@product.product_categories:

= @product.product_categories.inspect

输出是：

[#<ProductCategory id: 5, product_id: 9, category_id: 9, created_at: "2013-10-29 01:06:54", updated_at: "2013-10-29 01:06:54">, #<ProductCategory id: 6, product_id: 9, category_id: 7, created_at: "2013-10-29 01:06:54", updated_at: "2013-10-29 01:06:54">]

我认为这就是此处未选中各个复选框的原因：

= check_box_tag :product_categories_ids, category.id, @product.product_categories.include?(category), :name => 'product[product_categories_ids][]'

如何更新这部分，检查是否所有的复选框都应该被选中：

@product.product_categories.include?(category)

谢谢

【问题讨论】：

标签： ruby-on-rails ruby checkbox has-many-through

【解决方案1】：

错误在这一行：

 = check_box_tag :product_categories_ids, category.id, @product.product_categories.include?(category), :name => 'product[product_categories_ids][]'

如果我理解正确，您想检查产品类别数组是否包含给定的类别。如果是这样，你应该改变

`@product.product_categories.include?(category)`

到

`@product.categories.include?(category)`

【讨论】：