Duplicate mongoose Documents - node.js

Question

I'm looking for a very simple way to duplicate a document in my DB but can't find a way to do it.
I have 2 models with the exact same schema.
What i'm doing is
1stDB.findOne({id:"1"}, function(error, results){
if(!error){
var 2ndb = new 2nDB(results);
2nd.save(function (err) {
if (err) {
return err;
}
else {
console.log("SUCCESSFULL");
}
});
}
})
There seems to be an issue as in my console results is formatted properly but just wont save.
But if i do it manually : 2ndb.anyfield = anyvalue it works.
I think it might have to do with promise ? but i'm not very familiar with the concept and might be wrong.
I've tried this :
1stDB.findOne({id:"1"}, function(error, results){
if(!error){
var 2ndb = new 2nDB(**{results}**);
2nd.save(function (err) {
if (err) {
return err;
}
else {
console.log("SUCCESSFULL");
}
});
}
})
and this ( In the hope that deleting the _id and keeping my custom .id field to identify similar document but still having an uniq _id by document would work but it didn't )
1stDB.findOne({id:"1"}, function(error, results){
if(!error){
**var objectResponse = results;
delete objectResponse._id;**
var 2ndb = new 2nDB(results);
2nd.save(function (err) {
if (err) {
return err;
}
else {
console.log("SUCCESSFULL");
}
});
}
})

Answer 1

You can use the following to achieve the required results
1stDB.findOne({id:"1"}).lean().exec(function(error, results){
if(!error){
var objectResponse = results;
delete objectResponse._id;
var 2ndb = new 2nDB(objectResponse);
2nd.save(function (err) {
if (err) {
return err;
}
else {
console.log("SUCCESSFULL");
}
});
}
})
If the lean option is not used, mongoose will return a mongoose object instead of a simple json. This is why you were not able to pass the result directly to the constructor of the 2nd schema. Using the lean query the response will be a plain JSON object which can be passed to the constructor of the 2nd schema. For more information check this stackoverflow post on returning a plan object as response from mongoose