user.model.ts -

import { Prop, Schema, SchemaFactory } from '@nestjs/mongoose';
import { Document } from 'mongoose';
import * as mongoose from 'mongoose';
import { Req , Res } from '@nestjs/common';

export type UserDocument = User & Document;

@Schema()
export class User {
  constructor() {}
  @Prop({
    required: [true, 'Please enter first name'],
    trim: true,
  })
  firstName: string;

  @Prop({
    required: [true, 'Please enter last name'],
    trim: true,
  })
  lastName: string;

  @Prop({
    type: mongoose.Schema.Types.ObjectId,
    ref: 'User',
  })
  referer: mongoose.Types.ObjectId;

  @Prop({
    type: [
      {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'User',
      },
    ],
  })
  referees: mongoose.Types.ObjectId[];

  @Prop()
  referralCode: string;

  @Prop({
    default: 0,
  })
  transactions: number;

  @Prop({
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Account',
  })
  account: mongoose.Types.ObjectId;
}

export const UserSchema = SchemaFactory.createForClass(User);

UserSchema.pre('save', function ( req , res , next) {
  let referralCode;
  const random = Math.floor(Math.random() * 1000);
  const number = random.toLocaleString('en-US', {
    minimumIntegerDigits: 3,
    useGrouping: false,
  });
  const finalNumber = number.toString();
  const name = this.get('firstName');
  if (name.length < 5) {
    const repeat = 5 - name.length;
    const str = 'X';
    const repeatedString = str.repeat(repeat);
    referralCode = name.concat(repeatedString).concat(finalNumber);
  } else {
    referralCode = name.substr(0, 5).concat(finalNumber);
  }
  this.set('referralCode', referralCode);
  console.log(this);
  next();
});