使用 Mongo Mapper 删除 EmbeddedDocuments
我已经像这样设置了 mongo_mapper：
class Person
include MongoMapper::Document
many :pets
end
class Pet
include MongoMapper::EmbeddedDocument
key :animal, String
key :name, String
key :colour, String
end
# Create a person
me = Person.new
# Add pets to the person
me.pets << Pet.new(:animal => 'dog',:name => 'Mr. Woofs', :colour => 'golden')
me.pets << Pet.new(:animal => 'cat', :name => 'Kitty', :colour => 'black')
me.pets << Pet.new(:animal => 'cat', :name => 'Freckles', :colour => 'black')
me.pets << Pet.new(:animal => 'cat', :name => 'Fluffy', :colour => 'tabby')
我知道我可以非常简单地删除所有宠物（me.pets 作为一个数组工作，但也会回调）
# Delete all pets
me.pets.clear
我也知道我可以通过这样做删除所有黑猫：
# Delete black cats
me.pets.delete_if {|pet| pet.animal == 'cat' and pet.colour = 'black'}
但是如果有大量宠物需要迭代，那么似乎需要很长时间。
我觉得应该有一种方法可以只选择黑猫，然后清除那个数组。有这样的办法吗？
I have mongo_mapper set up like so:
class Person
include MongoMapper::Document
many :pets
end
class Pet
include MongoMapper::EmbeddedDocument
key :animal, String
key :name, String
key :colour, String
end
# Create a person
me = Person.new
# Add pets to the person
me.pets << Pet.new(:animal => 'dog',:name => 'Mr. Woofs', :colour => 'golden')
me.pets << Pet.new(:animal => 'cat', :name => 'Kitty', :colour => 'black')
me.pets << Pet.new(:animal => 'cat', :name => 'Freckles', :colour => 'black')
me.pets << Pet.new(:animal => 'cat', :name => 'Fluffy', :colour => 'tabby')
I know I can delete all pets very simply (me.pets works as an array but also calls back)
# Delete all pets
me.pets.clear
I also know that I could delete all black cats by doing this:
# Delete black cats
me.pets.delete_if {|pet| pet.animal == 'cat' and pet.colour = 'black'}
But that seems like it'll take a very long time if there are a large number of pets to iterate through.
I feel like there should be a way to select only the black cats and then clear that array instead. Is there such a way?
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尝试这样的事情，不知道这是否有效，但值得一试。
说实话，我认为你担心这个是多余的。通常数组操作非常快。
try something like this, no idea if this'll work but worth a shot.
To be honest though I think you are worrying about this for nothing. Usually array manipulation are plenty fast.