How to return the a formatted response from a mongo query/projection? - mongodb

Question

I'm trying to create an API to validate a promocode. I have minimal experience with mongo and the backend in general so I'm a bit confused in what is the best approach to do what I'm trying to accomplish.
I have this PromoCode form in the client. When a user types a promocode I would like for my backend to
verify if the code exists in one of the docs.
if it exists then return that code, the value for that code and the couponId
if the code doesn't exist then return an error.
My db is structured like this. The user will type one of those codes inside the codes: []
{
"_id": {
"$oid": "603f7a3b52e0233dd23bef79"
},
"couponId": "rate50",
"value": 50,
"codes": ["K3D01XJ50", "2PACYFN50", "COKRHEQ50"]
},
{
"_id": {
"$oid": "603f799d52e0233dd23bef78"
},
"couponId": "rate100",
"value": 100,
"codes": ["rdJ2ZMF100", "GKAAYLP100", "B9QZILN100"]
}
My route is structure like this:
router.post('/promoCode', (req, res, next) => {
const { promoCode } = req.body;
console.log('this is the req.body.promoCode on /promoCode', promoCode)
if (!promoCode) {
throw new Error('A promoCode needs to be passed')
}
promoCodesModel
.validatePromoCode(req.body.promoCode)
.then((response) => {
console.log('response inside /promoCode', response)
res.status(200).json({ data: response })
})
.catch((error) => {
res.status(400).json({ result: 'nok', error: error })
})
})
The validatePromoCode function is the following:
const validatePromoCode = async (code) => {
try {
let promoCode = await PromoCodesModel.find(
{"codes": code},
{_id: 0, codes: { $elemMatch: { $eq: code }} })
console.log('This is the promocode', promoCode)
return promoCode
} catch (err) {
throw new Error (err.stack)
}
}
All this seems to sort of work since I get the following response when the code is typed correctly
{
"data": [
{
"codes": [
"COKRHEQ50"
]
}
]
}
when typed incorrectly I get
{
"data": []
}
What I would like to get back is. (How can I accomplish this ?). Thanks
// when typed correctly
{
"data": { value: 50, couponId: "rate50", code: "COKRHEQ50" }
}
// when typed incorrectly
{
"error": "this is not valid code"
}
TL;DR: I would like to return a formatted query with specific values from a mongo query or an error object if that value does not exist on the document object.

Answer 1

Ok just figured it out
To be able to get the this responsed (what I wanted):
{
"data": [
{
"codes": [
"K3D01XJ50"
],
"couponId": "rate50",
"value": 50
}
]
}
I ended up having to do this on validatePromoCode
onst validatePromoCode = async (code) => {
try {
let promoCode = await PromoCodesModel.find(
{ codes: code },
{ _id: 0, codes: { $elemMatch: { $eq: code } }, couponId: 1, value: 1 },
)
return promoCode
} catch (err) {
throw new Error(err.stack)
}
}
But is there a better way on doing this ? Thanks