programming hero Tareq Rahman task solved

gistfile1.txt

app.get('/product/:key', (req, res) => {
    const key = req.params.key;
    client = new MongoClient(uri, { useNewUrlParser: true },{useUnifiedTopology: true});
    client.connect(err => {
        const collection = client.db("onlineStore").collection("products");
        collection.findOne({key},(err, documents)=>{
            if(err){
                console.log(err)
                res.status(500).send({message:err});
            }
            else{
                res.send(documents);
            }
        });
        client.close();
    });
});