条件语句失败 Rails 4

Question

我正在开发一个 Rails 应用程序，该应用程序具有在创建时分配了类别的 Pin 图。该应用程序共有 16 个类别。所有 Pin 图都显示在主索引页面上（类别 16 除外），用户可以单击 Pin 图，将它们带到 @Pin 的显示页面。 Show 页面有一个 @Pin 和一个从 db 中的所有 Pins 中选择的随机 Pin（类别 16 除外）。上面提到的动作是在pins控制器中定义的，并且正常运行。

The problem is when Category 16 is selected and the user proceeds to a Pins show page the Random Pin should be a Pin from Category 16 Only, but it is being selected from all the Pins in the db!

我已经在索引中设置了变量和条件语句，并显示了实现上述操作的动作，请在pins控制器show-action中查看我的cmets。问题代码在评论中仍然存在 ====SOMETHING WRONG!====

请帮助我对 Rails 比较陌生，我不确定我做错了什么，我花了几个小时尝试各种但没有任何效果。

pins_controller 索引操作

def index
if params[:category].blank?
  @restricted = Category.find(16) # category id 16 set as var @restricted used to exclude cat 16 from index page in line below.
  @pins = Pin.where.not(category: @restricted).all.order("created_at DESC").paginate(page: params[:page], per_page: 20)
else
  @category_id = Category.find_by(name: params[:category]).id
  @pins = Pin.where(category_id: @category_id).order("created_at DESC").paginate(page: params[:page], per_page: 20)
end 

pins_controller show-action 问题

def show
@pin.increment_view_count
@show_main_cat = Category.where.not(16) # all categories except category id 16 set as var @show_main_cat
if @show_main_cat.present? 
  @restricted = Category.find(16) # category id 16 set as var @restricted.
  @random_pin = Pin.where.not(id: @pin, category: @restricted).order("RANDOM()").first # select random pin from all categories except 16 + not @pin.
end
@show_restricted_cat = Category.find(16) # category 16 set as var @show_restricted_cat < ==========SOMETHING WRONG!==============
if @show_restricted_cat.present?
  @restricted = Category.where.not(16) # all categories except 16 set as var @restricted. 
  @random_pin = Pin.where.not(id: @pin, category: @restricted).order("RANDOM()").first # Only select random pin from category 16 + not @pin.
end

@reviews = Review.where(pin_id: @pin.id).order("created_at DESC").limit(5)
if @reviews.blank?
  @avg_review = 0
else
  @avg_review = @reviews.average(:rating).round(2)
end

Answer 1

这条线不是你所期望的

@random_pin = Pin.where.not(id: @pin, category: @restricted).order("RANDOM()").first # Only select random pin from category 16 + not @pin.

它将从类别 16 OR id not @pin 中随机选择一个 pin（我认为 来自类别 16 AND id not @pin）。将其更改为：

@random_pin = Pin.where.not(category: @restricted).where.not(id: @pin).order("RANDOM()").first

玩得开心！