在控制器动作中只显示具有相同属性的对象？

Question

<%= link_to categorization_path(categorization: :adventure) do %>    
  <span class="glyphicon glyphicon-picture", id="challenge-category"></span>
<% end %>
# There are other categories such as health, work, wacky, etc

routes.rb

get ":categorization", to: "pages#home", as: 'categorization'

此时，如果用户单击上面的link_to，我只想显示对categorization: adventure属性的挑战。

我需要在pages#home中放些什么才能让它工作呢？

pages_controller.rb

def home
 @challenges = current_user.challenges.order("deadline ASC")
 #How to only show one of the :categorization challenges if URL is root_path/:categorization?
end

challenge.rb

CATEGORIZATION = ['adventure', 'health', 'work', 'buy', 'wacky']
scope :adventure,  -> { where(categorizations: 'Adventure') }
scope :health,  -> { where(categorizations: 'health') }
scope :work,  -> { where(categorizations: 'Work') }
scope :buy,  -> { where(categorizations: 'Buy') }
scope :wacky,  -> { where(categorizations: 'Wacky') }
scope :goal,  -> { where(categories: 'Goal') }
scope :habit,  -> { where(categories: 'Habit') }

Answer 1

如果URL是root_path/:分类法，如何仅显示:分类挑战之一？

默认的@challenges已经返回一个有序的ActiveRecord::Relation对象。因此，您可以将一个scope链接到它。

class PagesController < ApplicationController
  # 1) using Rails method: `Object#try`
  # http://api.rubyonrails.org/classes/Object.html#method-i-try
  #
  def home
    # default challenges
    @challenges = current_user.challenges.order("deadline ASC")

    if home_params[:categorization]
      # `try` scope categorization param
      # `try` returns nil if param is invalid
      @challenges = @challenges.try(home_params[:categorization])

      # even if no results, empty AR object still returned
      #   => #<ActiveRecord::Relation []>
      #
      unless @challenges.is_a?(ActiveRecord::Relation)
        # do whatever here; remove placeholder on next line:
        raise "invalid categorization => #{home_params[:categorization]}"
      end
    end
  end

  # --OR--

  # 2) using Ruby method: `Object#send`
  # http://ruby-doc.org/core-2.3.1/Object.html#method-i-send
  #
  def home
    # default challenges
    @challenges = current_user.challenges.order("deadline ASC")

    if home_params[:categorization]
      @challenges = @challenges.send(home_params[:categorization])
    end

  rescue NoMethodError
    # do whatever here; remove placeholder on next line:
    raise "invalid categorization => #{home_params[:categorization]}"
  end



  private

  def home_params
    params.permit(:categorization)
  end
end

请参阅：http://guides.rubyonrails.org/active_record_querying.html#scopes

请参阅：http://guides.rubyonrails.org/action_controller_overview.html#strong-parameters

Answer 2

在您的操作中，尝试将当前行替换为以下一行：

@ current_user.challenges.send(params:categorization).order("deadline ASC")

它应该能工作