使用 Rails 3.2.我的模型是这样嵌套的:
Using Rails 3.2. My models are nested in such a way:
- 评论 => 可评论(国家或商店)
- 国家 => CountryDay => 商店 => 照片
- 商店 => 照片
我有以下几点:
@reviews = @user.reviews.includes(:user, :reviewable)通常我们可以通过以下方式包含嵌套多态:
Usually we can include nested polymorphic in such a way:
# this will return errors because :shop is not found in the model Shop (:reviewable is actually :shop) @reviews = @user.reviews.includes(:user, :reviewable => [:shop]) # this will return errors because :photos is not directly associated to Country @reviews = @user.reviews.includes(:user, :reviewable => :photos)还有许多其他变体.我如何解决这个问题,让 ActiveRecord 包含基于其关联的正确模型?
There are many other variants. How do I work around it to have the ActiveRecord includes the correct model based on its association?
推荐答案我想我刚才也遇到了同样的问题.尝试加载关联时出现 ActiveRecord::EagerLoadPolymorphicError.我的解决方案是将自定义连接语句放在一起,我已将其放入一个范围内以便于使用.
I think I had the same problem just now. I got an ActiveRecord::EagerLoadPolymorphicError when trying to load associations. My solution was to put together a custom join statement which I've put into a scope for easier usage.
未经测试,但这可能会让您前进:
Untested, but this may get you going:
class Review < ActiveRecord::Base scope :eagerly_loaded, -> { joins(' INNER JOIN shops ON (reviews.reviewable_type = "Shop" AND reviews.reviewable_id = shops.id) INNER JOIN countries ON (reviews.reviewable_type = "Country" reviews.reviewable_id = countries.id) ') } end然后您使用 @user.reviews.eagerly_loaded.确保使用匹配的 .group() 语句以仅获取您需要的语句.
You then use @user.reviews.eagerly_loaded. Make sure to use a matching .group()-statement to only get the ones you need.
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渴望加载不同的嵌套多态
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