Using findOne then save() to replace a document, mongoose - node.js

Question

I want to use the validation in my schema. Therefore i can't use findOneAndUpdate (?). I must use save.
Problem is, if I use findOne, then replaces the object with the one I'm going to replace it with, it will no longer have the save function.
mongoose.model('calculations').findOne({calcId:req.params['calcId']}, function(err, calculation){
if(err) {errHandler.serverErr(err, res, 'Something went wrong when trying to update a calculation'); return;}
calculation = calculationToReplace;
calculation.save(function(err, calc){ //No longer exists
if(err) {errHandler.serverErr(err, res, 'Something went wrong when trying to update a calculation'); return;}
res.send(200);
});
});
This must be a common task but I can't find any solution. How do I fix this?

Answer 1

There is a simple solution to your (by now really old) question.
In my case I had to have a findOneAndUpdate upsert that returned more information on what happened. So my solution was to step through the process to update the object with a for loop.
(Think the reason why you can't just copy is that the doc object contains a bunch of "extras" like version information and save function and other "bits"); So here is my solution.
exports.postData = function(req,res) {
console.log("will create " + req.body.alias);
console.log("It is level " + req.body.level); //OK, all this have to be changed to members of the data! req.body contains all the data sent from the user at this time
var query = { 'fulltext' : req.body.fulltext};
console.log("Checkking if " + req.body.fulltext + " exists")
Skill.findOne(query, function (err,doc){
if(err) return res.status(500).send(err)
if (!doc){
console.log(req.body.fulltext + " not found!")
var newdoc = new Skill(req.body);
newdoc.save(function(err){
if(err) return res.status(500).send(err)
console.log(newdoc.fulltext + " created as " + newdoc._id);
return res.status(200).send({_id: newdoc._id, alias: newdoc.alias})
})
return res.status(200).send('blal')
} else {
console.log(req.body.fulltext + " found!")
for (var id in req.body ){
doc[id]= req.body[id];
}
doc.save( function(err){
if(err) return res.status(500).send(err)
return res.status(200).send({_id: doc._id, alias: doc.alias})
})
//return res.status(200).send({_id: doc._id, alias: doc.alias})
}

Answer 2

I have not tested the following, so I am not sure if this works properly but it should probably be fine:
Swap this:
calculation = calculationToReplace;
with this:
for (var key in calculationToReplace)
if(typeof calculation[key] !== 'function')
calculation[key] = calculationToReplace[key];

Answer 3

Yes there is a way. You can read the mongoose documentation here. Take a look at the following code.
Tank.findById(id, function (err, tank) {
if (err) return handleError(err);
tank.size = 'large';
tank.save(function (err) {
if (err) return handleError(err);
res.send(tank);
});
});
This approach involves first retreiving the document from Mongo, then issuing an update command (triggered by calling save).