Mongo小组并推:推动所有领域 [英] Mongo group and push: pushing all fields

问题描述

是否有一种简单的方法可以"$ push"文档的所有字段? 例如:

Is there an easy way to "$push" all fields of a document? For example:

说我有一个Mongo藏书:

Say I have a Mongo collection of books:

{author: "tolstoy", title:"war & peace", price:100, pages:800}
{author: "tolstoy", title:"Ivan Ilyich", price:50,  pages:100}

我想按作者将它们分组-为每位作者列出他的整个图书对象:

I'd like to group them by author - for each author, list his entire book objects:

{ author: "tolstoy",
  books: [
     {author: "tolstoy", title:"war & peace", price:100, pages:800}
     {author: "tolstoy", title:"Ivan Ilyich", price:50,  pages:100}
  ]
}

我可以通过显式推送所有字段来实现此目的:

I can achieve this by explicitly pushing all fields:

{$group: {
     _id: "$author",
     books:{$push: {author:"$author", title:"$title", price:"$price", pages:"$pages"}},
}}

但是有什么捷径吗?

// Fictional syntax...
{$group: {
    _id: "$author",
    books:{$push: "$.*"},
}}

推荐答案

您可以使用$$ ROOT

You can use $$ROOT

{ $group : {
            _id : "$author",
            books: { $push : "$$ROOT" }
        }}

在这里找到:如何使用mongodb聚合并检索全部文档

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