Question

我正在创建一家服装店。我有类别有大小。女式衬衫（类别）可能有XS，S，M，Large。男式衬衫可以有XS，S，M，L。鞋子可以有4-16等等。

我创建了一个has_many through: association，用Category表和Sizes表连接Cateogry_Sizes表。

当管理员创建类别时，他们应该选择所有类别所需的大小。

如何在下方视图中选择尺寸？

当前代码不正确。在控制台中，当我转到category.sizes时，我只得到一个空数组。

查看：

<div class="container">
  <div class=“row”>
    <div class="col-md-6 col-md-offset-3">
      <div class="panel panel-primary">
        <div class="panel-body">
                    <%= simple_form_for(@category) do |f| %>
                      <div class="form-inputs">
                        <%= f.input :name %>
              <%= f.select(:sizes, Size.all.map {|s| [s.title, s.id]}, :multiple => true) %>
              <%= f.collection_select :parent_id, Category.order(:name), :id, :name, {prompt: "Select Parrent ID If Applicable"},include_blank: true %>
              <div class="form-actions"><%= f.button :submit %></div>
            </div>
          <% end %>
        </div>
      </div>
    </div>
  </div>
</div>

类别模型：

class Category < ActiveRecord::Base
    has_ancestry
    has_many :items
    validates :name, presence: true, length: { maximum: 20 }
  has_many :category_sizes
  has_many :sizes, through: :category_sizes
end

尺码型号：

class Size < ActiveRecord::Base
    validates :title, presence: true, length: { maximum: 15 }
    validates :title, uniqueness: true

  has_many :category_sizes
  has_many :categories, through: :category_sizes
end

Category_size模型：

class CategorySize < ActiveRecord::Base
  belongs_to :category
  belongs_to :size
end

架构：

ActiveRecord::Schema.define(version: 20150920013947) do

  create_table "categories", force: :cascade do |t|
    t.string   "name"
    t.string   "ancestry"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
  end

  add_index "categories", ["ancestry"], name: "index_categories_on_ancestry"

  create_table "category_sizes", force: :cascade do |t|
    t.integer  "category_id"
    t.integer  "size_id"
    t.datetime "created_at",  null: false
    t.datetime "updated_at",  null: false
  end

  add_index "category_sizes", ["category_id"], name: "index_category_sizes_on_category_id"
  add_index "category_sizes", ["size_id"], name: "index_category_sizes_on_size_id"

  create_table "items", force: :cascade do |t|
    t.string   "title"
    t.decimal  "price"
    t.text     "description"
    t.datetime "created_at",         null: false
    t.datetime "updated_at",         null: false
    t.integer  "user_id"
    t.string   "image_file_name"
    t.string   "image_content_type"
    t.integer  "image_file_size"
    t.datetime "image_updated_at"
    t.integer  "category_id"
  end

  add_index "items", ["user_id", "created_at"], name: "index_items_on_user_id_and_created_at"
  add_index "items", ["user_id"], name: "index_items_on_user_id"

  create_table "sizes", force: :cascade do |t|
    t.text     "title"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
  end

  create_table "taggings", force: :cascade do |t|
    t.integer  "tag_id"
    t.integer  "taggable_id"
    t.string   "taggable_type"
    t.integer  "tagger_id"
    t.string   "tagger_type"
    t.string   "context",       limit: 128
    t.datetime "created_at"
  end

  add_index "taggings", ["tag_id", "taggable_id", "taggable_type", "context", "tagger_id", "tagger_type"], name: "taggings_idx", unique: true
  add_index "taggings", ["taggable_id", "taggable_type", "context"], name: "index_taggings_on_taggable_id_and_taggable_type_and_context"

  create_table "tags", force: :cascade do |t|
    t.string  "name"
    t.integer "taggings_count", default: 0
  end

  add_index "tags", ["name"], name: "index_tags_on_name", unique: true

  create_table "users", force: :cascade do |t|
    t.string   "username"
    t.string   "email"
    t.datetime "created_at",                          null: false
    t.datetime "updated_at",                          null: false
    t.string   "password_digest"
    t.string   "remember_digest"
    t.boolean  "admin",               default: false
    t.string   "activation_digest"
    t.boolean  "activated",           default: false
    t.datetime "activated_at"
    t.string   "reset_digest"
    t.string   ">"
    t.datetime "reset_sent_at"
    t.string   "avatar_file_name"
    t.string   "avatar_content_type"
    t.integer  "avatar_file_size"
    t.datetime "avatar_updated_at"
    t.text     "description"
  end

  add_index "users", ["email"], name: "index_users_on_email", unique: true

end

控制器：

class CategoriesController < ApplicationController
  before_action :set_category,   only: [:show]
  before_action :admin_user,     only: [:destroy, :index, :edit, :show]

  def index
    @categories = Category.all
  end

  def show
    @tags = Item.where(category_id: @category.id).tag_counts_on(:tags)
    if params[:tag]
      @items = Item.tagged_with(params[:tag])
    else
      @items = Item.where(category_id: @category.id).order("created_at DESC")
    end
  end

  def new
    @category = Category.new
  end

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

  def create
    @category = Category.new(category_params)
    if @category.save
      redirect_to @category
      flash[:success] = "You have created a new category"
    else
      flash[:danger] = "Your category didn't save"
      render "new"
    end
  end

  def update
    @Cateogry = Category.find(params[:id])
    if @Cateogry.update(category_params)
       redirect_to @Cateogry
       flash[:success] = 'Category was successfully updated.'
    else
      render "edit"
    end
  end

  def destroy
    Category.find(params[:id]).destroy
    flash[:success] = "Category deleted"
    redirect_to categories_path
  end

  private

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

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

    # Confirms an admin user.
    def admin_user
      redirect_to(root_url) unless current_user.try(:admin?)
    end

end

以下是在控制台中发生的情况：

2.1.2 :026 > c = Category.last
  Category Load (0.3ms)  SELECT  "categories".* FROM "categories"  ORDER BY "categories"."id" DESC LIMIT 1
 => #<Category id: 57, name: "Test20", ancestry: "20", created_at: "2015-09-23 12:35:14", updated_at: "2015-09-23 12:35:14">
2.1.2 :027 > c.sizes
  Size Load (0.2ms)  SELECT "sizes".* FROM "sizes" INNER JOIN "category_sizes" ON "sizes"."id" = "category_sizes"."size_id" WHERE "category_sizes"."category_id" = ?  [["category_id", 57]]

以下是服务器日志中表单提交时发生的情况：

Started POST "/categories" for ::1 at 2015-09-23 22:37:28 +1000
Processing by CategoriesController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"4pMZ9PUr5yTSCNRiQeATljZsOIDeQCwhQPy9djEbAmejntpb8/DkK20JrMUeZkStsB5UU6YhbtExGwDKs7tT2Q==", "category"=>{"name"=>"test21", "sizes"=>"6", "parent_id"=>"20"}, "commit"=>"Create Category"}
Unpermitted parameter: sizes
  Category Load (0.1ms)  SELECT  "categories".* FROM "categories" WHERE "categories"."id" = ? LIMIT 1  [["id", 20]]
   (0.1ms)  begin transaction
  SQL (0.3ms)  INSERT INTO "categories" ("name", "ancestry", "created_at", "updated_at") VALUES (?, ?, ?, ?)  [["name", "test21"], ["ancestry", "20"], ["created_at", "2015-09-23 12:37:28.927360"], ["updated_at", "2015-09-23 12:37:28.927360"]]
   (1.0ms)  commit transaction
Redirected to http://localhost:3000/categories/58
Completed 302 Found in 5ms (ActiveRecord: 1.5ms)


Started GET "/categories/58" for ::1 at 2015-09-23 22:37:28 +1000
Processing by CategoriesController#show as HTML
  Parameters: {"id"=>"58"}

Answer 1

您需要允许控制器的参数中的大小如下：

<%= f.select(:sizes, Size.all.map {|s| [s.title, s.id]}, :multiple => true) %>

在你的表格中你应该改变：

<%= f.association :sizes %>

到

{{1}}

然后简单的形式应该做的魔术。另请参阅：https://github.com/plataformatec/simple_form#associations了解更多信息。

Answer 2

顺便说一句，我觉得有必要强调you may be able to use has_and_belongs_to_many使这项工作以目前的形式进行。它与has_many :through非常相似，只是它没有连接模型：

#app/models/category.rb
class Category < ActiveRecord::Base
   has_and_belongs_to_many :sizes
end

#app/models/size.rb
class Size < ActiveRecord::Base
   has_and_belongs_to_many :categories
end

这意味着您必须放弃category_sizes表，并将categories_sizes替换为category_id | size_id列：

如果您不想在连接模型中包含任何其他信息，则建议仅。例如，如果您想要包含库存水平或其他内容，has_many :through的联接模型将至关重要;不是你现在拥有它。

它还允许您致电：

@category = Category.find params[:id]
@category.sizes #-> collection of sizes for category.

-

<强>表格

HABTM也会使形式更简单：

<%= simple_form_for(@category) do |f| %>
    <%= f.input :name %>
    <%= f.collection_select :sizes, Size.all, :id, :name, { multiple: true } %>
    <%= f.collection_select :parent_id, Category.order(:name), :id, :name, {prompt: "Select Parent ID If Applicable"},include_blank: true %>
    <%= f.submit %>
<% end %>

#app/controllers/categories_controller.rb
class CategoriesController < ApplicationController
   def create
       @category = Category.new category_params
   end

   private

   def category_params
       params.require(:category).permit(:etc, :etc, :sizes)
   end
end

Has_many通过：category_sizes的关联

2 个答案: