Update and return document in mongodb - update and return document in mongodb

problem ：

I want to get updated documents. I want to get updated files .This is my original code and it successfully updates but doesn't return the document. This is my original code , It updates successfully but does not return documents .

collection.update({ "code": req.body.code },{$set:  req.body.updatedFields}, function(err, results) {                        res.send({error: err, affected: results});                        db.close();                    });

I used the toArray function, but this gave the error "Cannot use a writeConcern without a provided callback": I use the toArray function , But this gives the wrong “ If there is no callback provided , Can't use writeConcern”：

collection.update({ "code": req.body.code },{$set:  req.body.updatedFields}).toArray( function(err, results) {                    res.send({error: err, affected: results});                    db.close();                });

Any ideas? Do you have any ideas ？

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Solution ：

Reference resources ： https://stackoom.com/en/question/1fpsD