Question

我正在使用public_activity gem并在输出中，我正在检查可跟踪所有者是否与当前用户相同：

= a.owner == current_user ? 'You' : a.owner.name
did this activity

我在日志中收到了一堆缓存调用：

  User Load (1.8ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
  Rendered public_activity/post/_create.html.haml (1.4ms)
  Rendered public_activity/_snippet.html.haml (11.4ms)
  CACHE (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
  Rendered public_activity/post/_create.html.haml (13.9ms)
  Rendered public_activity/_snippet.html.haml (18.9ms)
  CACHE (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
  Rendered public_activity/comment/_comment.html.haml (0.9ms)
  Rendered public_activity/_snippet.html.haml (12.1ms)
  CACHE (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
  Rendered public_activity/comment/_comment.html.haml (2.7ms)
  Rendered public_activity/_snippet.html.haml (56.3ms)
  CACHE (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
  Rendered public_activity/comment/_comment.html.haml (0.6ms)
  Rendered public_activity/_snippet.html.haml (4.5ms)
  CACHE (0.0ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
  Rendered public_activity/content/_comment.html.haml (2.1ms)
  Rendered public_activity/_snippet.html.haml (9.5ms)

有没有办法急于加载条件？

Answer 1

@jverban是正确的，你可以比较记录ID，以避免不必要的记录加载。要回答关于急切加载的问题，是的，您可以使用ActiveRecord查询链中的includes方法急切加载。例如：

Activity.includes(:owner).latest

这将告诉Rails你打算引用owner关系，所以它们也应该被加载。

我强烈建议将bullet gem添加到您的项目中（仅在开发和测试环境中）以检测N + 1个查询，并在您遇到N + 1查询情况时发出警告。< / p>

Answer 2

您不需要加载用户记录，只需比较id属性

= a.owner_id == current_user.id ? 'You' : a.owner.name

如果多个活动所有者不是当前用户（获取所有者名称），则可能仍会发生缓存调用。

Rails - 提高重复if语句的性能

2 个答案: