如何在Rails 5中获得一个有作用域的父项的子项记录

Question

我需要一个控制器来传递符合特定范围的父项的子项记录。我希望这个范围在父记录上。

class Parent < ApplicationRecord 
    has_many :children 

    scope :not_blue, -> { where(blue:false) } 
    scope :blue,  -> { where(blue:true) } 

    # Subjective, may change in the future 
    scope :funny, -> { where('funny_scale>=?',5) } 

    scope :genies,  -> { blue.funny } 
end 

class Child < ApplicationRecord 
belongs_to :parent, required: true 
end 

class ChildrenController < ApplicationController 
    def index 
    # Yeah, this breaks horribly (and should), but you get my gist 
    @children_of_genies = Parent.genies.children 
    end 
end 

我知道答案可能是盯着我脸上，但谷歌搜索的正确组合正在逃避我。

Answer 1

如果您想您的解决方案仍然是一个ActiveRecord::Associations::CollectionProxy尝试Children.where(parent_id: Parent.genies.ids)你那么可以把进入范围。

scope: children_of_genies, -> { where(parent_id: Parent.genies.ids)

Answer 2

作用域返回ActiveRecord_Relation，得到children为它的每个成员可以使用collect：

@children_of_genies = Parent.genies.collect { |p| p.children }