猫鼬不会填充参考

Question

给定的是一个模型 UserModel

const UserSchema = mongoose.Schema(
  {
    username: {
      type: String,
      required: true,
      trim: true, // trim preceding spaces and trailing whitespaces
      index: { unique: true }, // the username should be unique
      minlength: 6,
    },
    email: {
      type: String,
      required: true,
      trim: true, // trim preceding spaces and trailing whitespaces
      lowercase: true, // normalize email addresses to lowercase
      index: { unique: true }, // the email address needs to be unique
    },
    password: {
      type: String,
      required: true,
      minlength: 8, // A password needs to be at least 8 characters long
      trim: true,
    },
    verified: {
      type: Boolean,
      default: false,
    },
    verificationToken: {
      type: String,
      required: true,
      index: true,
      unique: true,
      default: () => crypto.randomBytes(20).toString('hex'),
    },
    resetTokens: [{ type: mongoose.Schema.Types.ObjectId, ref: 'ResetToken' }],
  },
  {
    timestamps: true,
  }
);

module.exports = mongoose.model('User', UserSchema);

和密码重置令牌模型：

const PasswordResetTokenModel = mongoose.Schema(
  {
    _user: {
      type: mongoose.Schema.Types.ObjectId,
      required: true,
      index: true,
      ref: 'User',
    },
    token: {
      type: String,
      required: true,
      index: true,
      unique: true,
      default: () => crypto.randomBytes(20).toString('hex'),
    },
  },
  {
    timestamps: true,
  }
);
module.exports = mongoose.model('ResetToken', PasswordResetTokenModel);

如果我现在打电话

UserModel.find()
      .populate('resetTokens')
      .sort({ createdAt: -1 })
      .exec();

resetTokens 为空。

我以前做过，我知道这可能是微不足道的，但不知何故我无法弄清楚#是哪里出了问题。