Question

是否有可能通过习惯性 j子,如发现的_子,或更新。

具体案例一:我想到inc。 a 符合标准的一组文件。

It looks like this is possible in MongoDB: http://www.mongodb.org/display/DOCS/Updating#Updating-ModifierOperations

db.people.update( { name:"Joe" }, { $inc: { created_at : -1 } } );

But I don t thing Mongoid allows it (it seems to only let you inc one document at a time). And their update_all method I believe only can use $set. Thanks! http://mongoid.org/docs/querying/modification.html

举例来说,这并不奏效。

User.where(:name => "Joe").update_all("{ $inc: { created_at : -1 } }")

Answer 1

Mongoid提供Model#inc方法,但采用了一种检验方法,而不是一种分类方法。

但是,通过阅读<代码>的源代码。模型更新日期: 这种方法使你能够轻易地创建自己的<条码>inc。班级方法。

def update_all(attributes = {})
  klass.collection.update(
    selector,
    { "$set" => attributes },
    Safety.merge_safety_options(:multi => true)
  ).tap do
    Threaded.clear_safety_options!
  end
end

As you can see, Mongoid is passing the query to the underlying mongodb driver. The following method should work

class User
  def self.inc(field, value)
    klass.collection.update(
      selector,
      { "$inc" => { field => value } },
      Safety.merge_safety_options(:multi => true)
    ).tap do
      Threaded.clear_safety_options!
    end
  end
end

请指出: 我已经对它进行了检测。

Answer 2

B. 更新指挥时多国旗的投机者

http://www.mongodb.org

db.collection.update( criteria, objNew, upsert, multi )

multi - indicates if all documents matching criteria should be updated rather than just one. Can be useful with the $ operators below.

在你更新后指挥过程中树立了多条旗帜。

db.people.update( { name:"Joe" }, { $inc: { created_at : -1 } },false,true );

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