Question

I have the following Mongoose schema that embeds another:

var EmbedSchema = new Schema({
  foo: String
});

var ParentSchema = new Schema({
  foo: String
  embeds: [EmbedSchema]
});

After instantiating and embedding a couple objects, I’ll end up with something like this:

{
  "_id": "4f505a866e65f3896b00002c",
  "foo": "some value",
  "embeds: [
    {
      "_id": "4f505aa36e65f3896b000034",
      "foo": "some value 1"
    }, {
      "_id": "4f2eeb8f559757bf4f000001",
      "foo": "some value 2"
    }
  ]
}

Are the _ids within the embeds unique across the collection? I was thinking of querying just using embeds._id to get the Parent if it is.

Answer 1

If you allow mongo to create your _id field then they will all be unique in that collection.