Question

我有以下型号：

class Person < ApplicationRecord
    has_many :pets
end

class Pet < ApplicationRecord
    belongs_to :person
end

现在，我有一个包含某些宠物ID的数组，我想检查该人是否全部拥有它们。

_pets = [1, 4, 5]

person.owns(_pets)

所以现在我想了解如何检查用户是否拥有所有这些宠物。这意味着我想找出_pets是否是他所有宠物的子集。

class Person < ApplicationRecord
    has_many :pets

    def owns(_pets)
        # ???
        # Returns true or false
    end
end

class Pet < ApplicationRecord
    belongs_to :person
end

Answer 1

那这样的事情呢？

def owns(_pets)
  pets.where(id: _pets).size == _pets.size
end

Answer 2

我建议使用此选项。

class Person < ApplicationRecord
    has_many :pets

    def owns?(_pets)
        pets_ids = pets.pluck(:id)
        _pets.all? { |id| pets_ids.include? id }
    end
end

在_pets = [1, 4, 5]时，您可能遇到以下情况：

_pets =    [1, 4, 5]    # to checked
pets_ids = [1, 4]       # from pluck
#=> false


_pets =    [1, 4, 5]    # to checked
pets_ids = [1, 4, 5]    # from pluck
#=> true


_pets =    [1, 4, 5]    # to checked
pets_ids = [1, 4, 5, 6] # from pluck
#=> true

找出模型是否包含ID数组中描述的关联

2 个答案: