在控制器操作内部重构 params[...] 的许多 if 语句

Question

我有这样的代码，用于在我的表单中进行链选择 查看索引操作：

<%= form_tag do %>
    <%= collection_select(*@brands_select_params) %>
    <%= collection_select(*@car_models_select_params) %>
    <%= collection_select(*@production_years_select_params) %>
    <% # Пока еще никто ничего не выбрал %>
<%= submit_tag "Send", :id => "submit", :name => "submit" %>

和我的控制器：

class SearchController < ApplicationController
  def index
    @brands = Brand.all
    @car_models = CarModel.all

    if (params[:brand].blank?)
      @brands_select_params = [:brand, :id, @brands, :id, :name, :prompt => "Выбирай брэнд"]

      if params[:car_model].blank?
        @car_models_select_params = [:car_model, :id, @car_models, :id, :name, { :prompt => "Model" }, \
                                   { :disabled => "disabled" }]
        @production_years_select_params = [:production_year, :id, @car_models, :id, :name, { :prompt => "Year" }, \
                                         { :disabled => "disabled" }]
      end
    else
      @brands_select_params = [:brand, :id, @brands, :id, :name, { :selected => params[:brand][:id] } ]
      if params[:car_model].blank?
        @car_models_select_params = [:car_model, :id, Brand.find(params[:brand][:id]).car_models, :id, :name, \
                                   { :prompt => "And model now" } ]
        @production_years_select_params = [:production_year, :id, @car_models, :id, :name, { :prompt => "Year" }, \
                                         { :disabled => "disabled" } ]
      else
        @car_models_select_params = [:car_model, :id, Brand.find(params[:brand][:id]).car_models, :id, :name, \
                                   { :selected => params[:car_model][:id] } ] unless params[:car_model][:id].empty?
        @production_years_select_params = [:production_year, :id, CarModel.find(params[:car_model][:id]).production_years, :id, :year, \
                                         { :prompt => "And year now" } ] unless params[:car_model][:id].empty?
      end
    end
  end
end

如您所见，我的控制器代码中有太多 if 语句。我会在那里添加更多条件。此后，任何读过该代码的人都会受到大脑损坏。所以我只想以真正的 Ruby 方式实现它，但不知道如何。请帮忙，伙计们。我应该如何重构这堆废话？

Answer 1

我认为问题的很大一部分是你在控制器中做了太多的事情。生成标记（以及 IMO，包括为表单助手构建参数列表）应该在视图和视图助手中完成。所以：

module SearchHelper
  def brand_select brands, options={}
    collection_select :brand, :id, brands, :id, :name, :options
  end

  def car_model_select car_models, options={}
    collection_select :car_model, :id, car_models, :id, :name, options
  end

  def production_year_select years, options={}
    collection_select :production_year, :id, years, :id, :year, options
  end
end

然后你可以将你的控制器缩减为这样：

def index
  @brands     = Brand.all
  @car_models = CarModel.all

  @selected_brand_id      = params[:brand]      && params[:brand][:id]
  @selected_car_model_id  = params[:car_model]  && params[:car_model][:id]

  @production_years = @selected_car_model_id ?
    [] : CarModel.find(@selected_car_model_id).production_years
end

在你看来：

<%= brand_select @brands, :prompt   => "Выбирай брэнд",
                          :selected => @selected_brand_id
%>
<%= car_model_select @car_models, :prompt   => "Model",
                                  :selected => @selected_car_model_id
%>
<%= production_year_select @production_years, :prompt   => "Year",
                                              :selected => @selected_car_id
%>

我怀疑你可以使用 form_for 和 fields_for 并完全摆脱助手，但这在一定程度上取决于模型关联的设置方式。

Answer 2

此类问题没有明显的解决方案。

一般来说，我尝试保持 if / else 架构非常清晰，并将所有代码导出到单独的方法中。这里有两个优点：

• 可读性

• 更容易的单元测试

对于您的情况，这将是：

class SearchController < ApplicationController
  def index
    @brands = Brand.all
    @car_models = CarModel.all

    if (params[:brand].blank?)
      @brands_select_params = [:brand, :id, @brands, :id, :name, :prompt => "Выбирай брэнд"]
      if params[:car_model].blank?
        @car_models_select_params, @production_years_select_params =  get_card_model(@car_models)
      end
    else
      @brands_select_params = [:brand, :id, @brands, :id, :name, { :selected => params[:brand][:id] } ]
      if params[:car_model].blank?
        @car_models_select_params, @production_years_select_params = foo_method(@car_models)
      else
        @car_models_select_params, @production_years_select_params = bar_method
      end
    end
  end

  def get_card_model car_models
   [
    [:car_model, :id, car_models, :id, :name, { :prompt => "Model" }, { :disabled => "disabled" }],
    [:production_year, :id, car_models, :id, :name, { :prompt => "Year" }, { :disabled => "disabled" }]
    ]
  end
end