Mongo convert embedded document to array

Question

Is there a way to convert a nested document structure into an array? Below is an example:

Input

\"experience\" : {
        \"0\" : {         


        

Answer 1

See if this query works with your MongoDB version

For MongoDB version 3.2+:

db.doc.aggregate([
    {$project:{experience:["$experience.0"]}}
])

MongoDB < 3.2:

db.doc.aggregate([
    {$group: {_id:"$_id", experience:{$push:"$experience.0"}}}
])

It should transform your document into:

{ 
    "_id" : ObjectId("56f1b046a65ea8a72c34839c"), 
    "experience" : [
        {
            "duration" : "3 months", 
            "end" : "August 2012", 
            "organization" : {
                "0" : {
                    "name" : "Bank of China", 
                    "profile_url" : "http://www.linkedin.com/company/13801"
                }
            }, 
            "start" : "June 2012", 
            "title" : "Intern Analyst"
        }
    ]
}

A better approach if you want to alter documents in collection permanently using aggregation framework.

Lets assume your collection name is doc

db.doc.aggregate([
    {$group: {_id:"$_id", experience:{$push:"$experience.0"}}},
    {$out: "doc"}
])

Query above will transform all of your documents in place.