How to update Array Element in mongoose - MongoDB

Question

I am trying to update a MongoDb collection which has an array of document named items. I am using express and mongoose frameworks for this purpose.

Here is how my schema looks like:

const mongoose = require("mongoose");
const Schema = mongoose.Schema;
let invoices = new Schema({
 vendor: { type: String },
 invoiceDate: { type: Date, default: Date.now },
 expectedDate: { type: Date, default: Date.now },
 billingAddress: { type: String },
 contactPerson: { type: String },
 items: [
 {
 itemID: Schema.Types.ObjectId,
 qty: { type: Number },
 unitPrice: { type: Number },
 linePrice: { type: Number }
 }
 ],
 totalPrice: { type: Number }
});
module.exports = mongoose.model("invoices", invoices);

I want to update a certain document by first finding the id of that particular document and then update items accordingly.

This is what I tried so far and I don't know where to go next on updating the items which is an array.

//end-point-4
Routes.route('/update/:id').post((req, res) => {
 invoicesDB.findById(req.params.id, (err, invoice) => {
 if(!invoice){
 res.status(404).send('Not found!');
 }else{
 invoice.vendor = req.body.vendor;
 invoice.invoiceDate = req.body.invoiceDate;
 invoice.expectedDate = req.body.expectedDate;
 invoice.billingAddress = req.body.billingAddress;
 invoice.contactPerson = req.body.contactPerson;
 //how to update items
 invoice.items = req.body.items; //this I guess, gives the answer but not sure.
 invoice.totalPrice = req.body.totalPrice;
 }
 });
});

PS: I don't want to update a certain item in the items. What I want is to update the every item in the array with the given value.

For an example let's say the user only wants to update a particular item in the items, so only that particular item should be updated.

• O'Dane Brissett: You should consider i more dynamic approach. This approach will set the fields that are not sent in the request to null. Take a look at array filters as well docs.mongodb.com/manual/reference/operator/update/…

Answer 1

You can do with update straightforward as follows:

 invoicesDB.update(
 { "_id" : :req.params.id, "items._id": "Id of item for which
 user needs to update" }, 
 { "$set": { "items.$.qty": 5}}, 
 function(err, company) {
 console.log(company)
 })

• Lahiru Madusanka: This will update the every item with that qty which is I don't want.
• Subburaj: @Lahiru Madusanka it wont update all items it will update "items._id": "Id of item for which user needs to update" based on the condition for a particular item
• Lahiru Madusanka: So I have like many items. say 10. So I need to update each and every item. How can I achieve this? Should I write this end point to run 10 times (using a loop) for each item_id ?
• Subburaj: If you want to update 10 items, in one shot construct the array and user straightly` $set:{items:"constructed array"}
• Lahiru Madusanka: I don't get it. So how the items will be updated with their unique id if they are given with a constructed array? Can you give an example?

Answer 2

On mongoose, there is a '$' that indicates an array, and you can do this:

invoicesDB.update({_id: req.params.id}, {'$set': {
 'items.$.itemID': 'Here is where you update',
}}, function(err) { ... })