我在使用GraphQL和Mongoose（代码优先方法）的项目中遇到了一个小问题。我在用户的解析器中有一个findCurrentUser查询，它返回了关于当前已验证用户的信息，但我不想返回用户的密码，我如何避免这种情况？
用户解析器：

@Query(() => User)
@UseGuards(GqlAuthGuard)
async findCurrentUser(@CurrentUser() user: JwtPayload): Promise<User> {
  return await this.usersService.findCurrent(user.id);
}

字符串
用户服务：

async findCurrent(id: string): Promise<User> {
    try {
      // find the user
      const user = await this.userModel.findOne({ _id: id });

      // if the user does not exists throw an error
      if (!user) {
        throw new BadRequestException('User not found');
      }

      // we should not return the user's password
      // TODO: this is a temporary solution, needs to be improved
      user.password = '';

      return user;
    } catch (error) {
      throw new InternalServerErrorException(error.message);
    }
  }

型
用户实体：

import { ObjectType, Field, ID } from '@nestjs/graphql';
import { Schema, Prop, SchemaFactory } from '@nestjs/mongoose';
import { Document, Schema as MongooseSchema } from 'mongoose';
import { nanoid } from 'nanoid';

@Schema()
@ObjectType()
export class User {
  @Field(() => ID)
  _id: MongooseSchema.Types.ObjectId;

  @Field(() => String, { nullable: false })
  @Prop({ type: String, required: true, trim: true })
  firstName: string;

  @Field(() => String, { nullable: true })
  @Prop({ type: String, required: false, trim: true })
  lastName?: string;

  @Field(() => String, { nullable: true })
  @Prop({ type: String, required: false, default: nanoid(10) })
  username: string;

  @Field(() => String, { nullable: false })
  @Prop({
    type: String,
    unique: true,
    required: true,
    lowercase: true,
    trim: true
  })
  email: string;

  @Field(() => String, { nullable: false })
  @Prop({ type: String, required: true, trim: true, minlength: 6 })
  password: string;

  @Field(() => Boolean, { defaultValue: true })
  @Prop({ type: Boolean, default: true })
  isActive: boolean;

  @Field(() => Date, { defaultValue: Date.now() })
  @Prop({ type: Date, default: Date.now() })
  createdAt: Date;
}

export type UserDocument = User & Document;

export const UserSchema = SchemaFactory.createForClass(User);

型
在文档中，NestJS团队提到了“序列化“，但我已经尝试过了，没有工作。我在GraphQL Playground上得到了以下错误：
“message”：“无法为不可为空的字段User._id返回null。”