mongoose 如何仅在文档中存在请求时更新文档中的属性？

Question

In order to update a document i usually do as such...

  Model.findById(id)
.then((doc) => {
  doc.fName = req.body.fName
    ? req.body.fName
    : doc.fName;
  doc.lName = req.body.lName 
  ? req.body.lName
  : doc.lName
  return doc.save();
})
.then((result) => res.send(" Succesfully updated ! New data: " + result))
.catch((err) => res.send(err));

..which checks if the field actually exists in the body request,otherwise it just passes the previous value.

Is there a way to just provide the fields in the request and let it do the check for itself so if a field does not exist,it will not delete it? like so...

  Model.someMethod(id)
.then((doc) => {
  doc.fName = req.body.fName
  doc.lName = req.body.lName
  return doc.save();
})
.then((result) => res.send(" Succesfully updated ! New data: " + result))
.catch((err) => res.send(err));

Answer 1

Using it in this way will only update the same field that you enter in the req.body .Other fields will be as it is. Which is in the fields NOT_ALLOWED variable will not be updated.

const NOT_ALLOWED = ['_id'] //Just the same field will update which are not in this variable
     Model.findById(id).then((docs) => {
        Object.keys(req.body).map((key) => {

            if (NOT_ALLOWED.indexOf(key) === -1) {
                docs[key] = req.body[key]
            }

        })
        return docs.save()
    })
        .then((result) => console.log("Updated Data", result))
        .catch((err) => res.send(err));

Answer 2

You can do that with one update query. First, you can construct the update config based on all the properties from the req.body . Then, just pass that update config to the update query. You can also pass { new: true } as third config to update query, so the updated document will be returned.

let update = {};
if (req.body.fName) update.fName = req.body.fName;
if (req.body.lName) update.lName = req.body.lName;

Model.findByIdAndUpdate(id, update, { new: true })
  .then((result) => res.send(" Succesfully updated ! New data: " + result))
  .catch((err) => res.send(err));