重塑集合中的所有文档 [英] Reshape all the documents in the collection

问题描述

我的文档中具有以下结构:

I have the following structure in my documents:

{
    "_id" : 1,
    "item" : {
        "name" : "abc",
        "price" : 10,
        "quantity" : 2,
        "date" : ISODate("2014-03-01T08:00:00Z")
    }
}

我想在此上转换每个文档:

And I want to transform each document on this:

{
    "_id" : 1,
    "name" : "abc",
    "price" : 10,
    "quantity" : 2,
    "date" : ISODate("2014-03-01T08:00:00Z")
}

换句话说，删除嵌入的文档，但不删除细节！

In other words remove the embedded document but not the details!

谢谢！

推荐答案

您可以使用 aggregation ，尤其是 $project 运算符. $out 运算符可让您编写结果在另一个集合中.

You can use the aggregation especially the $projectoperator for that. The $out operator let you write the result in another collection.

db.collection.aggregate([
    { "$project": {
        "_id": "$_id", 
        "name": "$item.name",
        "price": "$item.price", 
        "quantity": "$item.quantity", 
        "date": "$item.date"}
    }, 
    { "$out": "collection"}
])

您的文档现在看起来像这样:

You documents now look like this:

{
    "_id" : 1,
    "name" : "abc",
    "price" : 10,
    "quantity" : 2,
    "date" : ISODate("2014-03-01T08:00:00Z")
}

您还可以通过给新结果集合使用相同的名称来覆盖现有的集合.

You can also overwrite the pre-existing collection by giving the new results collection the same name but this.

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