[Rails] 建立簡易 Category 方式

說明

此範例主要建立簡易的分類與下拉選單，例如：商店有分中式、日式、韓式等類型可選擇，將建立兩table進行類別對商店的1對多關連。

建立方式

1. 先建立 Model Category 及 category_id 欄位

rails g model Category name:string content:text

rails g migration add_category_id_to_shop category_id:integer

rake db:migrate

2. 建立關聯

class Shop < ActiveRecord::Base
  belongs_to :category
end
class Category < ActiveRecord::Base
  has_many :shops
end

3. 建立新增/編輯時的分類選項

<%= f.input :category_id, collection: Category.all, label_method: :name, value_method: :id, label: "category", include_blank: "請選擇..." %>

記得補上strong parameters

def shop_params
  params.require(:shop).permit(:category_id)
end

4. 建立分類資料

用seed或tasks或rails console建立

category = Category.create([
  { name: '中式菜餚' },
  { name: '日式料理' },
  { name: '韓式風味' }
])

5. 首頁的分類選單

<div class="list-group">
  <% @categories.each do |category|%>
    <%= link_to(category.name, shops_path(category: category),
      class: "list-group-item  #{"active" if current_page?(shops_path(category: category))}") %>
  <% end %>
</div>

6. Contorller調整

def index
  if params[:category].present?
   @shops = Shop.where(category_id: params[:category])
  else
   @shops = Shop.all
  end
end

參考

1. http://stackoverflow.com/questions/17758401/how-to-create-categories-in-rails
2. http://railscasts.com/episodes/37-simple-search-form
3. http://stackoverflow.com/questions/9879169/how-to-get-twitter-bootstrap-navigation-to-show-active-link