用mongoose和nestJS实现字段的自动递增

import { Schema, Prop, SchemaFactory } from '@nestjs/mongoose';
import { Document } from 'mongoose';

@Schema()
export class User extends Document {
  @Prop({ unique: true, required: true })
  username: string;

  @Prop({ required: true })
  password: string;

  @Prop({ default: 0 })
  count: number;
}

export const UserSchema = SchemaFactory.createForClass(User);

import { Injectable } from '@nestjs/common';
import { InjectModel } from '@nestjs/mongoose';
import { Model } from 'mongoose';
import { User } from './user.schema';

@Injectable()
export class UserService {
  constructor(@InjectModel(User.name) private userModel: Model<User>) {}

  async create(user: User): Promise<User> {
    const newUser = new this.userModel(user);
    newUser.count = await this.getNextCount(); // 自动递增字段的值
    return newUser.save();
  }

  private async getNextCount(): Promise<number> {
    const lastUser = await this.userModel.findOne().sort({ count: -1 }).exec();
    return lastUser ? lastUser.count + 1 : 1;
  }
}

import { Controller, Post, Body } from '@nestjs/common';
import { UserService } from './user.service';
import { User } from './user.schema';

@Controller('users')
export class UserController {
  constructor(private readonly userService: UserService) {}

  @Post()
  async create(@Body() user: User): Promise<User> {
    return this.userService.create(user);
  }
}