How to update a MongoDB document field only once? - node.js

Question

I'm trying to make a Mongoose query to run only once if the field inside the document hasn't been updated already, but I'm getting a bit lost with the $exist, $update, $ne - I don't know what to use really.
I have the following query:
const assignPhotoCodeToModel = (modelID, photoCode) => {
const filter = { id: modelID }
const update = { photoCode: photoCode }
const options = { new: true, useFindAndModify: false }
return new Promise((resolve, reject) => {
ModelModel.findOneAndUpdate(filter, update, options)
.then((response) => {
resolve(response)
})
.catch((error) => {
reject(error)
})
})
}
But I want this to run only if the field Model.photoCode is empty. If it already has a value, I just want it to return that value.
The problem I'm having is that every time the backend hits the route, a new photoCode gets assign to the model even if it has been already assigned. So it gets reassigned again again with a new one.
router.post(
'/payment/success',
(req, res, next) => {
...omitted_code...
photoCodeModel
.assignPhotoCodeToModel(req.body.modelId, photoCode)
... omitted_code
})
Edit 1
I'm writing this after trying the answers provided here. At first glance they seem to work, but now I'm getting into the error that when the Model.photoCode already has a value in it the return of the following function:
const assignPhotoCodeToModel = (modelID, photoCode) => {
//the difference is here
const filter = { id: modelID, photoCode : null }
const update = { $set: { photoCode: photoCode } }
const options = { new: true, useFindAndModify: false }
return new Promise((resolve, reject) => {
ModelModel.findOneAndUpdate(filter, update, options)
.then((response) => {
resolve(response)
})
.catch((error) => {
reject(error)
})
})
}
returns null, while I'm actually expecting the same model document to be returned. I'm guessing is because of the filtering? When I remove the photoCode : null it goes back to "working", but then I'm back to the problem that photoCode field gets populated with new values.
Basically I would like that function populates the filed photoCode once, but every subsequent call should just bring me back the same model document.

Answer 1

I think what you need is $set .
And, following your logic, I think you have to query "document that doesn't have photoCode yet".
It should be:
const assignPhotoCodeToModel = (modelID, photoCode) => {
//the difference is here
const filter = { id: modelID, photoCode : null }
const update = { $set: { photoCode: photoCode } }
const options = { new: true, useFindAndModify: false }
return new Promise((resolve, reject) => {
ModelModel.findOneAndUpdate(filter, update, options)
.then((response) => {
resolve(response)
})
.catch((error) => {
reject(error)
})
})
}

Answer 2

Write it in a neat asynchronous form. It will work.
const assignPhotoCodeToModel = async (modelID, photoCode) => {
const filter = { id: modelID, photoCode : null };
const update = { photoCode: photoCode };
const options = { new: true, useFindAndModify: false };
return await ModelModel.findOneAndUpdate(filter, update, options);
}