CODEWITHSUNDEEP
mongodb
Jorge
Jorge

Reputation: 83

How to look for in referenced document using MongoDB

I am working with MongoDB and I have a question:

Account: {
  _id: new ObjectId("<ID>"),
  name: "<NAME>"
}

User {
  _id: new ObjectId("<ID>"),
  email: "<EMAIL>",
  password: "<PASSWORD>",
  account: DBRef("accounts", ObjectId("<ID>"))
}

How can I look for users with and specific account name?

I tried:

db.users.find({"account.$name": "<NAME>"});

But it does not work.

How can I do it? Is it a good practice?

I appreciate any help.

Thanks in advance.

Upvotes: 1

Views: 28

Answers (1)

Buzz Moschetti
Buzz Moschetti

Reputation: 7578

"Back into it" with $lookup. First find the name you seek, then $lookup into the users collection. Simplfying here:

var r = [
     { id: "A", name: "buzz"}
     ,{ id: "B", name: "NOTbuzz"}
     ];
db.acct.drop();
db.acct.insert(r);


var r2 = [
      { email: "[email protected]", account: "A"}
      ,{ email: "[email protected]", account: "B"}
     ];

db.users.drop();
db.users.insert(r2);

db.acct.aggregate([
{$match: {"name": "buzz"}}
,{$lookup: { from: "users", localField: "id", foreignField: "account", as: "X"}}
                ]);

{
  "_id" : ObjectId("5a12007bfee383d2d2e74651"),
  "id" : "A",
  "name" : "buzz",
  "X" : [
    {
        "_id" : ObjectId("5a12007bfee383d2d2e74653"),
        "email" : "[email protected]",
        "account" : "A"
    }
  ]
}

Upvotes: 1

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