给定整数和uuid主键的表格集成多态连接(has_many)的最佳方式是什么？例如：
class Interest < ActiveRecord::Base # id is an integer has_many :likes,as: :likeable end class Post < ActiveRecord::Base # id is a UUID has_many :likes,as: :likeable end class User < ActiveRecord::Base has_many :likes has_many :posts,through: :likes,source: :likeable,source_type: "Post" has_many :interests,source_type: "Interest" end class Like < ActiveRecord::Base # likeable_id and likeable_type are strings belongs_to :likeable,polymorphic: true belongs_to :user end
许多查询工作：
interest.likes post.likes user.likes
然而：
user.interests
得到：
PG::UndefinedFunction: ERROR: operator does not exist: integer = character varying
LINE 1: …interests” INNER JOIN “likes” ON “interests”.”id” = “likes”….
^
HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.
: SELECT “interests”.* FROM “interests” INNER JOIN “likes” ON “interests”.”id” = “likes”.”likeable_id” WHERE “likes”.”user_id” = $1 AND “likes”.”likeable_type” = $2
什么是最好的方式来确保正确的铸造发生？
解决方法
我对ActiveRecord不是很好,这绝对不是你要找的答案,但如果你需要一个临时的*丑恶的解决方法,直到找到一个解决方案,你可以覆盖getter：
class User
def interests
self.likes.select{|like| like.likeable._type == 'Interest'}.map(&:likeable)
end
end
*非常丑,因为它将加载所有用户喜欢,然后排序
编辑我发现this interesting article：
self.likes.inject([]) do |result,like| result << like.likeable if like.likeable._type = 'Interest' result end