Complete controller code

complete_controller.js

const Product = require('./product_model');

module.exports.createProduct = async (req, res, next) => {
  const { name, sale_price, cost_price, quantity } = req.body;
  const newProduct = new Product({
    name,
    sale_price,
    cost_price,
    quantity,
  });

  newProduct.save((error, result) => {
    if (error) {
      res.json({ status: 'ERROR', message: 'Error creating product' });
    }

    if (result) {
      res.json({ status: 'SUCCESS', message: 'Product created' });
    } else {
      res.json({ status: 'FAILURE', message: 'Failed to create product' });
    }
  });
};

module.exports.viewProducts = async (req, res, next) => {
  Product.find({}).exec((error, result) => {
    if (error) {
      res.json({ status: 'ERROR', message: 'Error getting products' });
    }

    if (result.length > 0) {
      res.json({
        status: 'SUCCESS',
        message: 'Products found',
        products: result,
      });
    } else {
      res.json({ status: 'NO_PRODUCTS', message: 'No products found' });
    }
  });
};

module.exports.viewSingleProduct = async (req, res, next) => {
  Product.findOne({ _id: req.params.productId }).exec((error, result) => {
    if (error) {
      res.json({ status: 'ERROR', message: 'Error getting product' });
    }

    if (result) {
      res.json({
        status: 'SUCCESS',
        message: 'Product found',
        product: result,
      });
    } else {
      res.json({
        status: 'NO_PRODUCT',
        message: 'No product with specified product ID found',
      });
    }
  });
};

module.exports.updateProduct = async (req, res, next) => {
  Product.findOneAndUpdate(
    { _id: req.params.productId },
    {
      name: req.body.name,
      sale_price: req.body.sale_price,
      cost_price: req.body.cost_price,
      quantity: req.body.quantity,
    }
  ).exec((error, result) => {
    if (error) {
      res.json({ status: 'ERROR', message: 'Error updating product' });
    }

    if (result) {
      res.json({
        status: 'SUCCESS',
        message: 'Product details updated successfully',
      });
    } else {
      res.json({
        status: 'FAILURE',
        message: 'Failed to update product details',
      });
    }
  });
};

module.exports.deleteProduct = async (req, res, next) => {
  let { productId } = req.params;

  Product.findByIdAndDelete(productId, (error, result) => {
    if (error) {
      res.json({ status: 'ERROR', message: 'Error deleting product' });
    }

    if (result) {
      res.json({ status: 'SUCCESS', message: 'Product deleted' });
    } else {
      res.json({ status: 'FAILURE', message: 'Failed to delete product' });
    }
  });
};