有一个名为Location
的课程。我想在一个查询中预加载所有直接孩子。
在Location
中,类关系定义如下:
has_many :children,
class_name: self,
finder_sql: ->(query) {
self.class.where(%Q{"locations"."ancestry" like '%#{id}'}).to_sql
},
counter_sql: ->(query) {
self.class.where(%Q{"locations"."ancestry" like '%#{id}'}).count.to_sql
}
Location.first.children
Location Load (0.4ms) SELECT "locations".* FROM "locations" LIMIT 1
Location Load (0.3ms) SELECT "locations".* FROM "locations" WHERE ("locations"."ancestry" like '%1')
=> [#<Location id: 2, code: nil, name: "Niger 1349875728.873964", alternative_name: nil, ancestry: "1", coordinates: nil, ancestry_depth: 1>, (...)]
但是当我想要优化它并仅在两个批次中加载所有内容时:
Location.includes(:children).where(id: [5, 100]).all
Location Load (0.4ms) SELECT "locations".* FROM "locations" WHERE "locations"."id" IN (5, 100)
Location Load (0.2ms) SELECT "locations".* FROM "locations" WHERE "locations"."location_id" IN ('5')
ActiveRecord::StatementInvalid: PG::Error: ERROR: column locations.location_id does not exist
LINE 1: SELECT "locations".* FROM "locations" WHERE "locations"."lo...
^
: SELECT "locations".* FROM "locations" WHERE "locations"."location_id" IN ('5')
from /xxx/.rvm/gems/ruby-1.9.3-p194@gsp/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:1158:in `async_exec'
这是Rails中的错误,还是应该以不同的方式定义?
我也试图覆盖关系中的find_in_collection,但它没有任何影响。
答案 0 :(得分:0)
是的,你在那里对Rails做了太多的打击。在has_many:
上使用条件参数has_many :children, class_name: self, conditions: [%Q{"locations"."ancestry" like '%#{id}'}]
还只是想知道在那里使用吗?为什么不测试=?
has_many :children, class_name: self, foreign_key: :ancestry
此外,如果你走这条路,风格应该是_id:
has_many :children, class_name: self, foreign_key: :ancester_id