User Model:

const UserSchema = mongoose.Schema({
    userID: { type: String, unique: true },
    userName: String,
    password: String,
    isAdministrator: { type: Boolean, default: false }
});

ForumThread Model:

const ForumThreadSchema = mongoose.Schema({
    name: String,
    description: String,
    ownerID: //USERID FROM USER MODEL
});

Question: How can i use the userID from my User Model as the type from ownerID in ForumThread Model?