MongoDb聚合查找嵌套数组

Question

Lets say I have a MongoDB collection with docs like:

{
    _id,
    name: "someName",
    children:[
        ObjectId,
        ObjectId,
    ]
}

Is it possible to to a deep nest with child using the aggregation framework and lookup? Another problem is that we do not often know what the lookup field of the child is going to be, therefore the child has a "Lookup" array with the fields that should be looked up in the database.

So for example, the result would be with a depth of 3:

{
    _id,
    name: "someName",
    children:[
        {
            _id,
            name: "someName",
            children:[
                {
                    _id,
                    name: "someName",
                    children:[
                        ObjectId,
                        ObjectId,
                    ]
                }
                {
                    _id,
                    name: "someName",
                    children:[
                        ObjectId,
                        ObjectId,
                    ]
                }
            ]
        },
        {
            _id,
            name: "someName",
            children:[
                ObjectId,
                ObjectId,
            ]
        }
    ]
}

I would like to be able to create a function that enables me to specify the "depth" of the lookup.

We are using the mongodb NodeJs driver.

Answer 1

I see 2 solutions here:

1. To change your schema and try to use nested sets pattern. See https://docs.mongodb.com/manual/tutorial/model-tree-structures-with-nested-sets/

2. To make a recursive function to fetch all data you need, but you will face a problem such as N-aggregation method calls