Question

我正在使用will_paginate对群组中的帖子进行分页。一个论坛中可能有很多帖子，但我不想一次显示所有帖子。出于某些奇怪的原因，我注意到{groupscontroller *中显示的@group.posts = paginated_posts操作从数据库中删除了很多帖子。

我没有在@group上保存，为什么删除帖子？

先测试

 69     it "Pagination – get one group and its posts" do
 70       10.times { Fabricate(:post, group: @group, user: @user) }
 71       puts "POST COUNT BEFORE #{@group.posts.count}"
 72       # byebug
 73       get group_path(@group, posts_per_page: 3)
 74       puts "POST COUNT AFTER #{@group.posts.count}"
 75       expect(response).to have_http_status(200)
 76       expect(@group).to be_present
 77     end

测试输出

Groups
  GET /group/:group_id?posts_per_page=10&posts_page=2
POST COUNT BEFORE 12
POST COUNT AFTER 3

groups_controller.rb

  9   def show
 10     paginated_posts = @group.posts.paginate(
 11       page: params[:posts_page],
 12       per_page: params[:posts_per_page] || 100000,
 13     )
 14     @group.posts = paginated_posts
 15     render json: @group
 16   end

日志

  (0.3ms)  RELEASE SAVEPOINT active_record_1
Started GET "/groups/33?posts_per_page=3" for 127.0.0.1 at 2018-09-18 12:52:13 +0000
Processing by GroupsController#show as HTML
  Parameters: {"posts_per_page"=>"3", "id"=>"33"}
  User Load (2.1ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", "78913bd2-4c72-4c73-ba75-421e154c830b"], ["LIMIT", 1]]
  Group Load (1.4ms)  SELECT  "groups".* FROM "groups" WHERE "groups"."id" = $1 LIMIT $2  [["id", 33], ["LIMIT", 1]]
  Post Load (2.2ms)  SELECT  "posts".* FROM "posts" WHERE "posts"."group_id" = $1 LIMIT $2 OFFSET $3  [["group_id", 33], ["LIMIT", 3], ["OFFSET", 0]]
  Post Load (0.3ms)  SELECT "posts".* FROM "posts" WHERE "posts"."group_id" = $1  [["group_id", 33]]
   (0.4ms)  SAVEPOINT active_record_1
  Comment Load (0.5ms)  SELECT "comments".* FROM "comments" WHERE "comments"."post_id" = $1  [["post_id", 156]]
  PostImage Load (0.3ms)  SELECT "post_images".* FROM "post_images" WHERE "post_images"."post_id" = $1  [["post_id", 156]]
  Post Destroy (0.3ms)  DELETE FROM "posts" WHERE "posts"."id" = $1  [["id", 156]]
  Comment Load (0.3ms)  SELECT "comments".* FROM "comments" WHERE "comments"."post_id" = $1  [["post_id", 157]]
  PostImage Load (0.3ms)  SELECT "post_images".* FROM "post_images" WHERE "post_images"."post_id" = $1  [["post_id", 157]]
  Post Destroy (0.3ms)  DELETE FROM "posts" WHERE "posts"."id" = $1  [["id", 157]]
  Comment Load (0.3ms)  SELECT "comments".* FROM "comments" WHERE "comments"."post_id" = $1  [["post_id", 158]]

Answer 1

@group.posts = ...不能以您认为的方式工作。如果您具有一对多关系，并且将关联记录的数组分配给现有的group对象，则记录会设置并立即删除 group.id外键。无需保存。

所以当您这样做

@group.posts = paginated_posts

将分页的帖子分配给关联，并将关联中的所有其他记录从关联中删除。即刻。它们并不一定要删除，但它们不再属于@post

您可能想更改您的#to_json ...也许添加

attr_accessor :page_of_posts

然后在您的控制器中

@group.page_of_posts = paginated_posts

并确保page_of_posts是json中呈现的内容。其他人可能会建议一种更好的方法。

将帖子分页后，will_paginate删除群组中的帖子

1 个答案: