MongoDB $ project嵌入式文档到根级别

使用聚合管道，我试图将嵌入式文档投影到根级别，而不必单独投影每个字段。

例如，我要name从此集合投影到根级别：

[
    {
        _id: "1",
        name: {
            firstName: "John",
            lastname: "Peters"
        }
    },
    {
        _id: "2",
        name: {
            firstName: "Mary",
            lastname: "Jones"
        }
    }
]

这是我在寻找的东西：

[
    {
        firstName: "John",
        lastname: "Peters"
    },
    {
        firstName: "Mary",
        lastname: "Jones"
    }
]

有没有一种方法可以做到而不必单独投影每个字段？我不想这样做：

db.collection.aggregate(
    [
        {
            $project : {
                "_id" : 0,
                "firstName" : "$name.firstName",
                "lastName" : "$name.lastName"
            }
        }
    ]