Количество на складе

Question

Я использую Vue. js для этого.

У меня есть количество на складе. Я добавил функцию, чтобы уменьшить это число после отправки. Функция работает, она уменьшает значение, но после обновления или перезагрузки страницы количество возвращается в исходное состояние!

Как сделать количество постоянным?

Продукт. js Модель

    const mongoose = require('mongoose');
const HomeSchema = mongoose.Schema({
    name: String,
    title:String,
    category:String,
    image:String,
    description:String,
    detail:String,
    stock:Number,
    price:Number,
    star:Number,
    cast:String,
    director:String,
    isDeleted:{type: Boolean, default: false},
    updated_date: { type: Date, default: Date.now },
});
module.exports = mongoose.model('Products', HomeSchema);

А это и есть Маршрут продукта. js

var Products = require('../models/Products');
var express = require('express');
var mongoose = require('mongoose');
var router = express.Router();

var multer = require('multer');
var fs = require('fs');


var storage = multer.diskStorage({
  destination: (req, file, cb) => {
    cb(null, '../static/images/')
  },
  filename: (req, file, cb) => {
    let ext = file.originalname.substring(file.originalname.indexOf(".") + 1);
    cb(null, file.fieldname + '-' + Date.now() + "." + ext)
  }
});
var upload = multer({
  storage: storage
});

/* GET ALL products */
router.get('/', function(req, res, next) {
  Products.find(function (err, products) {
      if (err) return next(err);
      res.json(products);
    });
  });

/* GET SINGLE PRODUCT BY ID */
router.get('/:id', function(req, res, next) {
  Products.findById(req.params.id, function (err, post) {
      if (err) return next(err);
      res.json(post);
    });
  });

  /* SAVE PRODUCT 
router.post('/', function(req, res, next) {
  Products.create(req.body, function (err, post) {
      if (err) retu rn next(err);
      res.json(post);
    });
  });*/

  router.post('/', upload.single('image'),
    function (req, res) {
      let products = req.body;
      products.name = req.body.name
      products.title = req.body.title
      products.category = req.body.category
      products.image = req.body.image != 'undefined' ? req.file.filename : null
      products.price = req.body.price
      products.description = req.body.description
      products.detail = req.body.detail
      products.stock = req.body.stock
      products.star = req.body.star
      products.director = req.body.director
      products.cast = req.body.cast
      Products.create(products, function (err, post) {
        if (err) return next(err);
        res.json(post);
      });

  });

Это HTML

<input 
  type="submit" @click="decrement(product)" 
  class="btn btn-warning btn-user btn-block" value="Buy"
/>
<p class="text-danger text-center pt-2">
    <i class="fa fa-shopping-cart"></i>
    Only {{product.stock}} items left in stock!
</p>

Это функция, которую я использую (ПОЛНЫЙ СКРИПТ)

<script>
/* eslint-disable */
import { mapGetters } from "vuex";
import axios from 'axios'
export default {
  name: 'CreateBuyform',
  data () {
    return {
      rezervimet: {},
      prodId:this.$route.params.Pid,
      productfield:{},
    }
  },
    created() {
    axios.get(`http://localhost:4000/products`)

    .then(response => {
      this.productfield = response.data
    })
    .catch(e => {
      this.errors.push(e)
    })
     },
     computed: {
    ...mapGetters({
// map `this.user` to `this.$store.getters.user`
      user: "user"
    })
  },
  methods: {
     onSubmit(evt) {
      evt.preventDefault();



          var bodyFormData = new FormData();

          bodyFormData.set("prodid", document.getElementById("prodid").value);
          bodyFormData.set("userid", document.getElementById("userid").value);
          bodyFormData.set("address", document.getElementById("address").value);
          bodyFormData.set("phoneNumber", document.getElementById("phoneNumber").value);
          bodyFormData.set("city", document.getElementById("city").value);

          axios.post(`http://localhost:4000/rezervimet`, bodyFormData)
      .then(response => {
        //console.log(response);
        this.$router.push({
          name: '',
          //params: { id: response.data._id }
        })
        })
    },
    decrement(product){
      product.stock--;
      if(product.stock == 0){
        alert("No items in stock");
      }
    }
  }
}
</script>