I am receiving and Invoice Object through req.body. I am assigning the invoiceNumber before saving this object to the database (mongoose). When I assign invoiceNumber to invoicebody.invoiceNumber, it turns to be Undefined but, the result.invoiceNumber = 1.

router.post('/',async(req,res)=>{
try {
    let invoicebody = req.body;
    await VMaster.findOne({voucherType : 'INV'},{voucherNumber: 1, _id:0})
    .then( result =>{
        console.log ('First :', result.voucherNumber);
        invoicebody.invoiceNumber = result.invoiceNumber;
        console.log('Second :', invoicebody.invoiceNumber);
     });
     
   const invoice = await Invoice.create(invoicebody);
   Vitem.insertMany(invoicebody.itemCollection);
   res.status(200).json(invoice);
} catch (error) {
    console.log(error.message);
    res.status(500).json({message : error.message});
}
})

Console.Log