Question

我有一个用户的favourite_guidelines数组。在我的控制台中，它看起来像这样：

fg=User.first.favourite_guidelines
  User Load (73.9ms)  SELECT "users".* FROM "users" LIMIT 1
  FavouriteGuideline Load (0.2ms)  SELECT "favourite_guidelines".* FROM "favourite_guidelines" WHERE "favourite_guidelines"."user_id" = 11
 => [#<FavouriteGuideline id: 16, guideline_id: 24, user_id: 11, created_at: "2013-02-17 01:03:19", updated_at: "2013-02-17 01:03:19">, #<FavouriteGuideline id: 18, guideline_id: 23, user_id: 11, created_at: "2013-02-17 11:40:27", updated_at: "2013-02-17 11:40:27">]

因此它包含两条准则。我希望能够删除某个guideline_id的值，以便用户最喜欢的指南可以删除该收藏夹。目前我有：

User.first,favourite_guidelines.delete_if{|favourite| favourite["guideline_id"] == 24}

这让我：

.9.3p194 :066 > User.first.favourite_guidelines.delete_if{|favourite| favourite["guideline_id"] == 24}
  User Load (0.4ms)  SELECT "users".* FROM "users" LIMIT 1
  FavouriteGuideline Load (0.3ms)  SELECT "favourite_guidelines".* FROM "favourite_guidelines" WHERE "favourite_guidelines"."user_id" = 11
 => [#<FavouriteGuideline id: 18, guideline_id: 23, user_id: 11, created_at: "2013-02-17 11:40:27", updated_at: "2013-02-17 11:40:27">]'

所以看起来它正在删除它，但它显然没有保存，因为如果我这样做：

    1.9.3p194 :067 > User.first.favourite_guidelines
  User Load (0.4ms)  SELECT "users".* FROM "users" LIMIT 1
  FavouriteGuideline Load (0.4ms)  SELECT "favourite_guidelines".* FROM "favourite_guidelines" WHERE "favourite_guidelines"."user_id" = 11
 => [#<FavouriteGuideline id: 16, guideline_id: 24, user_id: 11, created_at: "2013-02-17 01:03:19", updated_at: "2013-02-17 01:03:19">, #<FavouriteGuideline id: 18, guideline_id: 23, user_id: 11, created_at: "2013-02-17 11:40:27", updated_at: "2013-02-17 11:40:27">]

我做错了什么？

Answer 1

delete_if适用于返回记录的数组但不适用于数据库。尝试：

User.first.favourite_guidelines.where(guideline_id: 24).destroy_all

PS。你也可以看here

Answer 2

试试这个：

   User.first.favourite_guidelines.destroy( :guideline_id => 24)

或者

  User.first.favourite_guidelines.where( :guideline_id => 24).destroy_all

试图从数组中删除 - rails

2 个答案: