mongoose Model.save() returns null data in NodeJS

Question

I am trying to add a product document to the MongoDB by using mongoose v5.6.3 in NodeJS, but in callback function, it cannot assign result to the returning value.

Here is my function:

public async addProduct(productInfo: Product) {
        let result = null;

        let newProduct = new ProductModel(productInfo);
        newProduct.uuid = id();

        await newProduct.save(async (err,product) => {
            if(err){
                throw new ProductCreateError();
            }
            result = product;
        });
        return result;
    }

Note that, Product and ProductModel are different but same in terms of parameters. Product is an interface and ProductModel is a mongoose model.

When this function is called, it returns the initial value of 'result'

Problem might occur because of async/await but im not sure. How can I fix this?

Badri · Accepted Answer · 2019-07-22 11:51:07Z

2

Since save() is a asynchronous task it will always return null.The function will return null before returning product.

modify the code as

public async addProduct(productInfo: Product) {
let result = null;
  try {
    let newProduct = new ProductModel(productInfo);
    newProduct.uuid = id();
    result = await newProduct.save();
  } catch (e) {
    throw new ProductCreateError();
  }
}

Try this code and let me know.

answered Jul 22, 2019 at 11:51

Badri

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1 Comment

HARUN SASMAZ Over a year ago

Dude sorry for the late answer and this works fine! Thank you a lot

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