MongoDB and Nested Arrays

Question

I have a collection with data like this:

{
    "Name": "Steven",
    "Children": [
        {
            "Name": "Liv",
            "Children": [
                {
                    "Name": "Milo"
                }
            ]
        },
        {
            "Name": "Mia"
        },
        {
            "Name": "Chelsea"
        }
    ]
},
{
    "Name": "Ozzy",
    "Children": [
        {
            "Name": "Jack",
            "Children": [
                {
                    "Name": "Pearl"
                }
            ]
        },
        {
            "Name": "Kelly"
        }
    ]
}

Two questions

Can MongoDB flatten the arrays to a structure like this [Steven, Liv, Milo, Mia,Chelsea, Ozzy, Jack, Pearl,Kelly]
How can I find the a document where name is jack, no matter where in the structure it is placed

1- the answer is $unwind (aggregation) stackoverflow.com/questions/26463032/searching-in-mongodb/… 2- stackoverflow.com/questions/26463032/searching-in-mongodb/… — Disposer
– Disposer, Commented Nov 10, 2014 at 21:00
@Disposer: Thank you for your input. Isn't $unwind used to generate a document for each element in the array? You posted the same link twice. — CruelIO
– CruelIO, Commented Nov 11, 2014 at 6:33
@CruelIO you want two different output like first contains array of all name and seconds contains which match Children.Name="jack" or Children.Children.Name="jack" is right? — Neo-coder
– Neo-coder, Commented Nov 11, 2014 at 9:31

wdberkeley · Accepted Answer · 2014-11-11 16:30:49Z

2

In general, MongoDB does not perform recursive or arbitrary-depth operations on nested fields. To accomplish objectives 1 and 2 I would reconsider the structure of the data as an arbitrarily nested document is not a good way to model a tree in MongoDB. The MongoDB docs have a good section of modelin tree structures that present several options with examples. Pick the one that best suits your entire use case - they will all make 1 and 2 very easy.

answered Nov 11, 2014 at 16:30

wdberkeley

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