Stop Mongoose from creating _id property for sub-document array items

Question

If you have subdocument arrays, Mongoose automatically creates ids for each one. Example:

{
    _id: "mainId"
    subDocArray: [
      {
        _id: "unwantedId",
        field: "value"
      },
      {
        _id: "unwantedId",
        field: "value"
      }
    ]
}

Is there a way to tell Mongoose to not create ids for objects within an array?

Answer 1

It's simple, you can define this in the subschema :

var mongoose = require("mongoose");

var subSchema = mongoose.Schema({
    // your subschema content
}, { _id : false });

var schema = mongoose.Schema({
    // schema content
    subSchemaCollection : [subSchema]
});

var model = mongoose.model('tablename', schema);

Answer 2

You can create sub-documents without schema and avoid _id. Just add _id: false to your subdocument declaration.

var schema = new mongoose.Schema({
   field1: {
      type: String
   },
   subdocArray: [{
      _id: false,
      field: { type: String }
   }]
});

This will prevent the creation of an _id field in your subdoc.

Tested in Mongoose v5.9.10

Answer 3

Additionally, if you use an object literal syntax for specifying a sub-schema, you may also just add _id: false to supress it.

{
   sub: {
      property1: String,
      property2: String,
      _id: false
   }
}

Answer 4

I'm using mongoose 4.6.3 and all I had to do was add _id: false in the schema, no need to make a subschema.

{
    _id: ObjectId
    subDocArray: [
      {
        _id: false,
        field: "String"
      }
    ]
}

Answer 5

You can use either of the one

var subSchema = mongoose.Schema({
//subschema fields    

},{ _id : false });

or

var subSchema = mongoose.Schema({
//subschema content
_id : false    

});

Check your mongoose version before using the second option

Answer 6

If you want to use a predefined schema (with _id) as subdocument (without _id), you can do as follow in theory :

const sourceSchema = mongoose.Schema({
    key : value
})
const subSourceSchema = sourceSchema.clone().set('_id',false);

But that didn't work for me. So I added that :

delete subSourceSchema.paths._id;

Now I can include subSourceSchema in my parent document without _id. I'm not sure this is the clean way to do it, but it work.