我在Rails控制台中遇到以下查询：
Listing.joins(:colors, :sizes, :product, :orders).pluck('colors.id', 'sizes.id', 'products.id', 'orders.id')
(4.5ms) SELECT colors.id, sizes.id, products.id, orders.id FROM "listings" INNER JOIN "colors" ON "colors"."listing_id" = "listings"."id" INNER JOIN "sizes" ON "sizes"."listing_id" = "listings"."id" INNER JOIN "products" ON "products"."id" = "listings"."product_id" INNER JOIN "orders" ON "orders"."listing_id" = "listings"."id"
和
Listing.joins(:colors, :sizes, :product, :orders).select('colors.id', 'sizes.id', 'products.id', 'orders.id')
Listing Load (4.6ms) SELECT colors.id, sizes.id, products.id, orders.id FROM "listings" INNER JOIN "colors" ON "colors"."listing_id" = "listings"."id" INNER JOIN "sizes" ON "sizes"."listing_id" = "listings"."id" INNER JOIN "products" ON "products"."id" = "listings"."product_id" INNER JOIN "orders" ON "orders"."listing_id" = "listings"."id"
并分别得到以下结果：
[[2, 3, 1, 1], [2, 3, 1, 2], [2, 2, 1, 1], [2, 2, 1, 2], [2, 1, 1, 1], [2, 1, 1, 2], [3, 3, 1, 1], [3, 3, 1, 2], [3, 2, 1, 1], [3, 2, 1, 2], [3, 1, 1, 1], [3, 1, 1, 2], [4, 3, 1, 1], [4, 3, 1, 2], [4, 2, 1, 1], [4, 2, 1, 2], [4, 1, 1, 1], [4, 1, 1, 2]]
和
#<ActiveRecord::Relation [#<Listing id: 1>, #<Listing id: 2>, #<Listing id: 1>, #<Listing id: 2>, #<Listing id: 1>, #<Listing id: 2>, #<Listing id: 1>, #<Listing id: 2>, #<Listing id: 1>, #<Listing id: 2>, ...]>
请帮助这让我感到困惑。
你感到困惑与所提供结果的格式pluck和select。pluck在简单数组中返回结果，其中作为select活动记录关系的返回数组。这就是为什么您获得与不同格式相同的结果的原因。
希望它能消除您的疑问。
输出为pluck：
[[2, 3, 1, 1], [2, 3, 1, 2]..]
输出为select：
#<ActiveRecord::Relation[#<Listing id: 1>, #<Listing id: 2>..]
本文收集自互联网，转载请注明来源。
如有侵权，请联系[email protected] 删除。
我来说两句