how to only update specific fields and leave others with the previous values in findandupdate with Mongoose

Question

I've created an update function using Mongoose. However whenever I update the data using findOneAndUpdate. It updates only the fields entered and making it so that the others are now null or empty. I would like it so that when the user is updating and they dont update a filed it should remain as what it was before instead of being empty now. essentially only update the fields entered.

heres my routes

router.post("/updateStock", (req, res) => {
    const filter = {prodId: req.body.prodID}

    const update = req.body

    Product.findOneAndUpdate(filter, update, {new: true}).then((product) => {
        console.log("success");
        res.send(product);
  }).catch(err => {
       console.log("err", err);
       res.status(500).send(err);
  })

});

here's an example of req.body. I've only updated the title and catergory on the frotnend meaning everything else is blank. When it saves in the DB it ony updates the title and catergory and leaves everything else blank. I would like it to not insert the blank ones into the DB and leave the fields as they are

{
  prodId: 'iPhone 111001200',
  title: 'iPhone 11 Pro',
  manufacturer: '',
  catergory: 'Electronics',
  price: '',
  quantity: ''
}

Here's my model

const mongoose = require("mongoose");

const Product = mongoose.model(
  "Product",
  new mongoose.Schema({
    title: String,
    manufacturer: String,
    price: String,
    catergory: String,
    quantity: String,
    prodID: String, 
    images: Array
  })
);

module.exports = Product;

Answer 1

Something like this then:

const update = {};
for (const key of Object.keys(req.body)){
    if (req.body[key] !== '') {
        update[key] = req.body[key];
    }
}
test.findOneAndUpdate(filter, {$set: update}, {new: true}).then((product) => {
        console.log("success");
        res.send(product);
  }).catch(err => {
       console.log("err", err);
       res.status(500).send(err);
  })}

You should use the $set only to update the fields that you want to update. In your case, the fields that are not '' .

Answer 2

This function converts your payload into mongoose update query

 function convertObject(obj, parentKey = '') { // Create an empty result object const result = {}; // Iterate over the keys of the original object for (const key in obj) { // Check if the value is an object if (typeof obj[key] === 'object') { // Call the function recursively to convert the nested object // Pass the parent key as an argument to append it to the nested keys Object.assign(result, convertObject(obj[key], `${parentKey? `${parentKey}.`: ''}${key}`)); } else { // Add the key to the result object with the same value // Use the parent key to create the full key in the format key1.key2.key3... result[`${parentKey? `${parentKey}.`: ''}${key}`] = obj[key]; } } // Return the result object return result; } // Test the function const originalObject = { doc: { sub_doc: { nested_doc: 'text' } } }; console.log(convertObject(originalObject)); // Output: { 'doc.sub_doc.nested_doc': 'text' }