Change document structure in mongodb with the mongo shell [duplicate]

问题

This question already has an answer here:

Reshape all the documents in the collection (1 answer)

Closed 3 years ago.

I have a document structure in mongodb and i want to change it for all my documents without using aggregate function like this response but by creating a specific function, and have a result from that :

{
"_id" : ObjectId("String"),
"content" : {
    "href" : "String",
    "text" : "String",
    "code" : "String "
}
}

to that :

{
"_id" : ObjectId("String"),
"href" : "String",
"text" : "String",
"code" : "String "
}

Any suggestions please. Thank you.

回答1:

If you do not fancy aggregation (or your content's content may differ across documents) you can also use

 db.coll.find().forEach(function (d) {
    db.coll.update({
        _id : d._id
    }, {
        $set : d.content,
        $unset : {
            'content' : 1
        }
    })
});

回答2:

The easiets way to do it is to use aggregation framework. Then save output into newCollection and after verification you can delete old one and rename created one.

db.collection.aggregate([{
            $project : {
                _id : 1,    
                href : "$content.href",
                text : "$content.text",
                code : "$content.code",    
            }
        }, {
            $out : "newCollection"
        }
    ])

来源：https://stackoverflow.com/questions/37486849/change-document-structure-in-mongodb-with-the-mongo-shell