Rails 3包含translations globalize3 activerecord

Question

我有这样的模式:帖子类别和类别has_many帖子。帖子和类别使用gem globalize3进行全球化

class Post < ActiveRecord::Base
  belongs_to :category
  translates :title, :excerpt, :desc # globalize3
end

class Category < ActiveRecord::Base
  has_many :posts
  translates :name # globalize3
end

在我的PostsController中，所有的帖子都是用这行代码写的：

def index
  @posts = Post.includes([:translations, {:category => :translations}])
end

问题是我在使用category转换表时遇到了n+1查询问题：

Post Load (0.3ms)  SELECT "posts".* FROM "posts"

Post::Translation Load (0.3ms)  SELECT "post_translations".* FROM "post_translations" WHERE ("post_translations".post_id IN (2,3,4))

# START n+1 query block
Category Load (1.9ms)  SELECT "categories".* FROM "categories" WHERE ("categories"."id" IN (9,12,11))
Category::Translation Load (0.4ms)  SELECT "category_translations".* FROM "category_translations" WHERE ("category_translations".category_id = 9) AND ("category_translations"."locale" IN ('it'))
CACHE (0.0ms)  SELECT "category_translations".* FROM "category_translations" WHERE ("category_translations".category_id = 9) AND ("category_translations"."locale" IN ('it'))
Category::Translation Load (0.2ms)  SELECT "category_translations".* FROM "category_translations" WHERE ("category_translations".category_id = 12) AND ("category_translations"."locale" IN ('it'))
CACHE (0.0ms)  SELECT "category_translations".* FROM "category_translations" WHERE ("category_translations".category_id = 12) AND ("category_translations"."locale" IN ('it'))
Category::Translation Load (0.2ms)  SELECT "category_translations".* FROM "category_translations" WHERE ("category_translations".category_id = 11) AND ("category_translations"."locale" IN ('it'))
CACHE (0.0ms)  SELECT "category_translations".* FROM "category_translations" WHERE ("category_translations".category_id = 11) AND ("category_translations"."locale" IN ('it'))
# END n+1 query block

Category::Translation Load (0.5ms)  SELECT "category_translations".* FROM "category_translations" WHERE ("category_translations".category_id IN (9,12,11))

如何解决这个n+1查询问题？

Answer 1

您应该在模型中启用翻译的即时加载。建议执行此操作的方法是：

class Category < ActiveRecord::Base
  has_many :posts
  translates :name # globalize3

  default_scope includes(:translations)
end

Answer 2

Rails 4,5,6：从MichałSzajbe那里得到的答案是，这仍然可以通过轻微的修改来工作：

class Category < ActiveRecord::Base
  has_many :posts
  translates :name

  default_scope { includes(:translations) }
end