Question

我和这篇帖子Rails ActiveRecord sort by count of join table associations几乎有相同的情况，但我无法让它发挥作用。

我有一张名为coffeeshops的表格，其中users的表格可以通过名为favorite_coffeeshops的第三个表格来收藏咖啡店。我正在使用acts_as_taggable gem。

class Coffeeshop < ApplicationRecord
  has_many :favorite_coffeeshops# just the 'relationships'
  has_many :favorited_by, through: :favorite_coffeeshops, source: :user

class FavoriteCoffeeshop < ApplicationRecord
  belongs_to :coffeeshop
  belongs_to :user

class User < ApplicationRecord
  has_many :coffeeshops
  has_many :favorite_coffeeshops # just the 'relationships'
  has_many :favorites, through: :favorite_coffeeshops, source: :coffeeshop

在我的控制器中，我有以下内容：

def index
....

@favshops = Coffeeshop.select
('coffeeshops.*, count(favorite_coffeeshops.coffeeshop_id) as favorite_coffeeshops_count')
.joins(:favorite_coffeeshops.group(:favorite_coffeeshops.coffeeshop_id)
.order('favorite_coffeeshops DESC')
end

在我甚至可以检查查询是否正确之前，我实际上遇到了语法错误。这是将字符串包装在多行中吗？

SyntaxError (/Users/Simon/gourmet_coffee/app/controllers/home_controller.rb:12: syntax error, unexpected keyword_end, expecting ')'
  end
     ^
/Users/Simon/gourmet_coffee/app/controllers/home_controller.rb:17: syntax error, unexpected end-of-input, expecting keyword_end):

Answer 1

语法错误告诉您，期望)字符关闭括号，但会转到end语句。

如果你看这一行：

.joins(:favorite_coffeeshops.group(:favorite_coffeeshops.coffeeshop_id)

（根据您的语法错误应该是第12行），然后您可以看到有两个开放的(字符，但只有一个关闭)。

因此，要修复语法错误，只需在调用)方法之前为joins方法添加缺少的group，即：

.joins(:favorite_coffeeshops).group(:favorite_coffeeshops.coffeeshop_id)

在Rails 5

1 个答案: