Mongodb array of documents vs array of objects

Question

Can you tell me when array of documents should be used and when array of objects should be used ?

These links will light up http://openmymind.net/Multiple-Collections-Versus-Embedded-Documents/ and http://stackoverflow.com/questions/5373198/mongodb-relationships-embed-or-reference — Digital Alchemist, Nov 03 '16 at 18:45

score 0 · Answer 1 · answered Nov 03 '16 at 14:24

By array of objects I'm assuming you mean ObjectId's AKA references to other collections, since a document is just a JSON object anyway.

The basic paradigm of data modeling is to embed whenever possible. If your collection references a finite number such a user's list of phone numbers like this - you definitely want to embed.

{
  phone_numbers: [
    {
      type: "mobile",
      number: "(123)456-7890"
    },
    {
      type: "home",
      number: "(456)789-0123"
    }
  ]
}

If you are referencing a 1 <--> Many or 1 <--> Very Many collection, that is when you want to use references such as messages sent/received to a user.

{
  from: ObjectId, // Reference to ObjectId of the sender
  to: [], // Array of ObjectId references
  message: String,
  date: Date
}

I highly advise reading here:

https://docs.mongodb.com/v3.2/core/data-model-design/

Mongodb array of documents vs array of objects

1 Answers1