Nested maps in mongoose schema

Question

I'm currently creating a fitting mongoose schema for our new JSON format. It is not very complex but I ran into the issue that certain values are not saved as array but rather as "normalized array" like this:

answers: [{value: 5, string: "abc"}, {value: 4, string: "def"}]

will be:

answers: {
           1: {id: 1, value: 5, string: "abc"},
           2: {id: 2, value: 4, string: "def"}
       }

The Objects themselves can have nested "normalized arrays" as well.

For now I tried using mongoose type "Map" in the top-level-Schema like this:

 answers: {
    type: Map,
    of: answer
}

Where "answer" is a separate mongoose.Schema itself. But all I get is:

    TypeError: Undefined type `Map` at `answers`
  Did you try nesting Schemas? You can only nest using refs or arrays.

Why can't I just nest maps as expected? Is it even possible to project this "normalize array" structure in a mongoose schema, and if so, how?

Thank for reading!

Answer 1

I was in the same situation and it seems to work for me:

const ChildSchema = new Schema({
  firstName: String,
});

const ParentSchema = new Schema({
  name: String,
  mapProperty: { type: Map, of: ChildSchema },
});

I do also get the validation triggered from mongoose on the ChildSchema so it seems to accept it just fine.

Hope it helps.