ruby-on-rails - 在 Rails 中重构一个复杂的过滤器

Question

我正在尝试处理一个有点复杂的查询。我已经阅读了一些关于如何处理这个问题的方法，但它们在这里并不真正适用，因为这不像一个复杂的搜索表单（比如在 vBulletin 搜索帖子表单上），而是一组过滤两者的路由按“类别”（未发布、流行、最新）和“时间”（所有时间、上个月、上周、今天）

我意识到下面的代码非常糟糕。我的目标只是让它工作，然后重构。更不用说，它甚至没有真正起作用，因为它没有考虑到类别和时间，只是一个或另一个，但我想我会在这个线程中处理这个问题。

此外，为了使这个 SO 代码粘贴更清晰，我.page(params[:page]).per(30)从每一行中排除了，但是它需要继续所有这些。

那么，有谁知道我该怎么做呢？我已经考虑了一段时间，有点难过

def index
  case params[:category]
  when "latest"
    @books = Book.all.page(params[:page]).per(30)   
  when "downloads"
    @books = Book.order('downloads DESC')
  when "top100"
    @books = Book.order('downloads DESC').limit(100)
  when "unreleased"
    @books = Book.unreleased
  else
    @books = Book.all.page(params[:page]).per(30)   
  end

  case params[:time]
  when "today"
    @books = Book.days_old(1)
  when "week"
    @books = Book.days_old(7)
  when "month"
    @books = Book.days_old(30)
  when "all-time"
    @books = Book.all
  else
    @books = Book.all.page(params[:page]).per(30)   
  end
end

路线：

# Books
get 'book/:id', to: 'books#show', as: 'book'

resources :books, only: [:index] do
  get ':category/:time(/:page)', action: 'index', on: :collection
end

score 8 · Accepted Answer

将所有查询作为范围移动到模型

class Book < ActiveRecord::Base
  scope :downloads,  -> { order('downloads DESC') }
  scope :top100,     -> { order('downloads DESC').limit(100) }
  scope :unreleased, -> { unreleased }
  scope :today,      -> { days_old(1) }
  scope :week,       -> { days_old(7) }
  scope :month,      -> { days_old(30) }
  scope :latest,     -> { }
  scope :all_time,   -> { }
end

创建辅助方法来过滤参数并避免不匹配的数据

class BooksController < ApplicationController
  private

  def category_params
    %w(downloads top100 unreleased).include?(params[:category]) ? params[:category].to_sym : nil
  end

  def time_params
    %w(today week month latest all_time).include?(params[:time]) ? params[:time].to_sym : nil
  end
end

case通过应用与参数同名的范围来摆脱语句

def index
  query = Book.all
  query = query.send(category_params) if category_params
  query = query.send(time_params) if time_params
  @books = query.page(params[:page]).per(30)
end

在四行中，我们仍在Sandi Metz 指导方针的范围内！:)

score 2 · Accepted Answer

例如，在 Rails 中，您可以“链接”查询

   Book.where(:released => true).where(:popular => true)

是相同的

   Book.where(:released => true, popular => true)

您可以使用它来帮助您进行重构。这是我的看法：

   def index

      # Start with all books, we are going to add other filters later
      query = Book.scoped

      # Lets handle the time filter first   
      query = query.where(['created_at > ?', start_date] if start_date

      case params[:category]
      when "latest"
        query = query.order('created_at DESC')
      when "downloads"
        query = query.order('downloads DESC')
      when "top100"
        query = query.order('downloads DESC').limit(100)
      when "unreleased"
        query = query.where(:released => false)
      end

      # Finally, apply the paging
      @books = query.page(params[:page]).per(30)

end

    private

    def start_date
      case params[:time]
      when "today"
        1.day.ago 
      when "week"
        7.days.ago
      when "month"
        1.month.ago
      when "all-time"
        nil
      else
        nil
      end
    end

ruby-on-rails - 在 Rails 中重构一个复杂的过滤器

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