Error while updating a document in MongoDB

July 3, 2022

I am having an admin portal in which I am handling all the collections that exist in my Mongo database. Now, I am building the update operations. I want to find a user that exist with his username and update the document with the changes that the admin performed.

For that reason, in my controller I have an endpoint which do the following:

exports.updateUser = async(req, res) => {
  try{
    var user = new User({
      firstName: req.body.firstName,
      lastName: req.body.lastName,
      username:req.body.username,
      password: req.body.password,
      email: req.body.email
    });
    const static_username = req.body.static_username;

    await User.findOneAndUpdate({static_username} , user, { useFindAndModify: false})
    .then(data => {
        if(!data){
          res.status(404).send({ message : `Cannot Update user with ${id}. Maybe user not found!`})
        }else{
          res.redirect('/admin');
        }
    })
    .catch(err =>{
        res.status(500).send({ message : "Error Update user information"})
    })
  } catch {
    console.log(err);
  }
}

It takes the changes that the admin has made from the body and it puts them into user object. I also set to the variable static_username the username before update in order to find the user I to make the update.

I am getting a response that exist inside the catch of the query:

{ message : "Error Update user information"}

Error:

MongoServerError: Plan executor error during findAndModify :: caused by :: Performing an update on the path '_id' would modify the immutable field '_id'

Any thoughts why found user doesn’t get updated?

>Solution :

You are sending a User object which has an _id field by default. So, unknowingly you are trying to modify the _id field and setting it to zero. To solve this, you can simply send a normal object.

var user = {
      firstName: req.body.firstName,
      lastName: req.body.lastName,
      username:req.body.username,
      password: req.body.password,
      email: req.body.email
};