Mongo search through nested document array

Question

I have a mongo document as follows i want to be able to do make two searches:

1) search for id= 123 2) serach for id= 1234

So the document i need could be the top level or nested.

{
   "id": "123",
   "name" : "testName",
   "docs": [
   {
   "id": "1234",
   "name" : "testName4",
   "docs": []
    }
   ]
}

So basically i could need the top document or the nested document. Im looking at graph lookup but i dont think that will do what i need, i also looked at aggregates - seems like they would work?

You can have good reference over here

Rohan Shukla
– Rohan Shukla

2019-02-28 10:22:29 +00:00
Commented Feb 28, 2019 at 10:22 — Rohan Shukla
– Rohan Shukla, Commented Feb 28, 2019 at 10:22

Developer Ol · Accepted Answer · 2019-02-28 11:22:07Z

Can you clarify, what your results should look like?

If you want to search for documents which have an id of "123" or contain a document in "docs" with the id "1234" you could simply query for:

db.teststack.find({$or: [{"id": "123"}, {"docs.id": "1234"}]})

which will always return the complete document.

EDIT

See this example I've written:

db.teststack.mapReduce(
function(){
    let scanfunction = (passobj) => {
        if(passobj.id === "123") {
            emit("id123", this._id);
        }
        else {
            for(var key in passobj) {
                if(typeof passobj[key] === "object"){
                    scanfunction(passobj[key]);
                }
            }
        }
    }

    scanfunction(this);
}
,
function(key, stuff){
let ret = "";
for(let t1 in stuff)
ret += stuff[t1] + ";";
return ret;
}
,
{
"out": "keys"
}
).find()

It simply returns a string containing all ObjectIds which

a: have the id: "123"
b: contain a document with id: "123"
c: contain a document containing a doc.... of which at least one has the id: "123"

The Code is scalable, as it scans all keys of all documents in your database, but therefore it is not performant!

If you don't know your Database format before, you can use a mapReduce() query to execute JavaScript-Code serverside and display the results as you wish. However, this is not very performant, so I would recommend you to solve your Problem by a different Database-Scheme, where you can predict nestings.

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