使用 has-many-through 关联编辑/更新 collection_select

Question

我有以下模型：RECIPE、TAG 和 TAGGING（连接表）

食谱.rb

has_many :taggings
has_many :tags, through: :taggings
accepts_nested_attributes_for :taggings

标签.rb

has_many :taggings
has_many :recipes, through: :taggings

scope :diet, -> { where(type_id: 1).to_a }
scope :category, -> { where(type_id: 2).to_a }
scope :festivity, -> { where(type_id: 3).to_a }
scope :daily, -> { where(type_id: 4).to_a }

到目前为止一切正常。但是，在我的 TAGS 表中，我有一个名为“type_id”的字段，它为我带来了一种标签分类。所以我创建了一些“范围”来区分彼此。

tagging.rb

belongs_to :recipe
belongs_to :tag, :counter_cache => :recipes_count

recipes_controller.rb

def new
    @recipe = Recipe.new
    @recipe.tags.build
    @recipe.taggings.build(:recipe => @recipe)
end

def edit
end

我的表格

= f.fields_for :taggings, @recipe.taggings.build do |builder| 
    = builder.collection_select :tag_id, Tag.diet, :id, :name

= f.fields_for :taggings, @recipe.taggings.build do |builder| 
    = builder.collection_select :tag_id, Tag.category, :id, :name

= f.fields_for :taggings, @recipe.taggings.build do |builder| 
    = builder.collection_select :tag_id, Tag.festivity, :id, :name

= f.fields_for :taggings, @recipe.taggings.build do |builder| 
    = builder.collection_select :tag_id, Tag.daily, :id, :name

当我创建一个新配方时，标签通常会添加到连接表（标签）中。但是当我编辑 collection_select 帮助器时，并没有将项目标记为“已选择”。

如何构造多范围的collection_select？

如何为 EDIT/UPDATE 操作构造 collection_select？

还有其他更好的方法吗？

Answer 1

它对我有用：

= f.fields_for :taggings, @recipe.taggings.order("id").first do |diet|
    = diet.collection_select :tag_id, Tag.diet, :id, :name

= f.fields_for :taggings, @recipe.taggings.order("id").second do |category| 
    = category.collection_select :tag_id, Tag.category, :id, :name

= f.fields_for :taggings, @recipe.taggings.order("id").third do |festivity| 
    = festivity.collection_select :tag_id, Tag.festivity, :id, :name

= f.fields_for :taggings, @recipe.taggings.order("id").fourth do |daily| 
    = daily.collection_select :tag_id, Tag.daily, :id, :name

Answer 2

试试

= f.fields_for :taggings, @recipe.taggings do |builder| 

代替

= f.fields_for :taggings, @recipe.taggings.build do |builder| 

因为您每次都返回新标签，而不是重复使用之前创建的标签。