I want to get the sum of quantity only for the itemID that match the parameter :id but im getting an array of all ids sum. whats wrong with the code here?

// get Sum of Sold Qty 
    app.get('/soldqty/:id', async (req, res) => {
        const id = req.params.id;
        const item = { _id: ObjectId(id) };
        const cursor = await soldCollection.aggregate([
            {
                $group:
                    { _id: "$itemId", TotalSum: { $sum: 1 } }
            }

        ]
        );
        const restul = await cursor.toArray();
        console.log(restul);
        res.send(restul);
    })